diff --git a/packages/backend/src/core/NoteCreateService.ts b/packages/backend/src/core/NoteCreateService.ts
index fb36ca3b6..4f3d66dd5 100644
--- a/packages/backend/src/core/NoteCreateService.ts
+++ b/packages/backend/src/core/NoteCreateService.ts
@@ -570,12 +570,14 @@ export class NoteCreateService implements OnApplicationShutdown {
 			if (data.reply) {
 				// 通知
 				if (data.reply.userHost === null) {
-					const threadMuted = await this.noteThreadMutingsRepository.findOneBy({
-						userId: data.reply.userId,
-						threadId: data.reply.threadId ?? data.reply.id,
+					const isThreadMuted = await this.noteThreadMutingsRepository.exist({
+						where: {
+							userId: data.reply.userId,
+							threadId: data.reply.threadId ?? data.reply.id,
+						}
 					});
 
-					if (!threadMuted) {
+					if (!isThreadMuted) {
 						nm.push(data.reply.userId, 'reply');
 						this.globalEventService.publishMainStream(data.reply.userId, 'reply', noteObj);
 
@@ -712,12 +714,14 @@ export class NoteCreateService implements OnApplicationShutdown {
 	@bindThis
 	private async createMentionedEvents(mentionedUsers: MinimumUser[], note: Note, nm: NotificationManager) {
 		for (const u of mentionedUsers.filter(u => this.userEntityService.isLocalUser(u))) {
-			const threadMuted = await this.noteThreadMutingsRepository.findOneBy({
-				userId: u.id,
-				threadId: note.threadId ?? note.id,
+			const isThreadMuted = await this.noteThreadMutingsRepository.exist({
+				where: {
+					userId: u.id,
+					threadId: note.threadId ?? note.id,
+				},
 			});
 
-			if (threadMuted) {
+			if (isThreadMuted) {
 				continue;
 			}
 
diff --git a/packages/backend/src/core/NoteReadService.ts b/packages/backend/src/core/NoteReadService.ts
index b84591e26..52e9bd369 100644
--- a/packages/backend/src/core/NoteReadService.ts
+++ b/packages/backend/src/core/NoteReadService.ts
@@ -43,11 +43,13 @@ export class NoteReadService implements OnApplicationShutdown {
 		//#endregion
 
 		// スレッドミュート
-		const threadMute = await this.noteThreadMutingsRepository.findOneBy({
-			userId: userId,
-			threadId: note.threadId ?? note.id,
+		const isThreadMuted = await this.noteThreadMutingsRepository.exist({
+			where: {
+				userId: userId,
+				threadId: note.threadId ?? note.id,
+			},
 		});
-		if (threadMute) return;
+		if (isThreadMuted) return;
 
 		const unread = {
 			id: this.idService.genId(),
@@ -62,9 +64,9 @@ export class NoteReadService implements OnApplicationShutdown {
 
 		// 2秒経っても既読にならなかったら「未読の投稿がありますよ」イベントを発行する
 		setTimeout(2000, 'unread note', { signal: this.#shutdownController.signal }).then(async () => {
-			const exist = await this.noteUnreadsRepository.findOneBy({ id: unread.id });
+			const exist = await this.noteUnreadsRepository.exist({ where: { id: unread.id } });
 
-			if (exist == null) return;
+			if (!exist) return;
 
 			if (params.isMentioned) {
 				this.globalEventService.publishMainStream(userId, 'unreadMention', note.id);
diff --git a/packages/backend/src/core/SignupService.ts b/packages/backend/src/core/SignupService.ts
index e6b17a874..1e44406c1 100644
--- a/packages/backend/src/core/SignupService.ts
+++ b/packages/backend/src/core/SignupService.ts
@@ -71,12 +71,12 @@ export class SignupService {
 		const secret = generateUserToken();
 
 		// Check username duplication
-		if (await this.usersRepository.findOneBy({ usernameLower: username.toLowerCase(), host: IsNull() })) {
+		if (await this.usersRepository.exist({ where: { usernameLower: username.toLowerCase(), host: IsNull() } })) {
 			throw new Error('DUPLICATED_USERNAME');
 		}
 
 		// Check deleted username duplication
-		if (await this.usedUsernamesRepository.findOneBy({ username: username.toLowerCase() })) {
+		if (await this.usedUsernamesRepository.exist({ where: { username: username.toLowerCase() } })) {
 			throw new Error('USED_USERNAME');
 		}
 
diff --git a/packages/backend/src/core/UserFollowingService.ts b/packages/backend/src/core/UserFollowingService.ts
index 7d90bc2c0..4d7bfeaf2 100644
--- a/packages/backend/src/core/UserFollowingService.ts
+++ b/packages/backend/src/core/UserFollowingService.ts
@@ -122,22 +122,26 @@ export class UserFollowingService implements OnModuleInit {
 			let autoAccept = false;
 
 			// 鍵アカウントであっても、既にフォローされていた場合はスルー
-			const following = await this.followingsRepository.findOneBy({
-				followerId: follower.id,
-				followeeId: followee.id,
+			const isFollowing = await this.followingsRepository.exist({
+				where: {
+					followerId: follower.id,
+					followeeId: followee.id,
+				},
 			});
-			if (following) {
+			if (isFollowing) {
 				autoAccept = true;
 			}
 
 			// フォローしているユーザーは自動承認オプション
 			if (!autoAccept && (this.userEntityService.isLocalUser(followee) && followeeProfile.autoAcceptFollowed)) {
-				const followed = await this.followingsRepository.findOneBy({
-					followerId: followee.id,
-					followeeId: follower.id,
+				const isFollowed = await this.followingsRepository.exist({
+					where: {
+						followerId: followee.id,
+						followeeId: follower.id,
+					},
 				});
 
-				if (followed) autoAccept = true;
+				if (isFollowed) autoAccept = true;
 			}
 
 			// Automatically accept if the follower is an account who has moved and the locked followee had accepted the old account.
@@ -206,12 +210,14 @@ export class UserFollowingService implements OnModuleInit {
 
 		this.cacheService.userFollowingsCache.refresh(follower.id);
 
-		const req = await this.followRequestsRepository.findOneBy({
-			followeeId: followee.id,
-			followerId: follower.id,
+		const requestExist = await this.followRequestsRepository.exist({
+			where: {
+				followeeId: followee.id,
+				followerId: follower.id,
+			},
 		});
 
-		if (req) {
+		if (requestExist) {
 			await this.followRequestsRepository.delete({
 				followeeId: followee.id,
 				followerId: follower.id,
@@ -505,12 +511,14 @@ export class UserFollowingService implements OnModuleInit {
 			}
 		}
 
-		const request = await this.followRequestsRepository.findOneBy({
-			followeeId: followee.id,
-			followerId: follower.id,
+		const requestExist = await this.followRequestsRepository.exist({
+			where: {
+				followeeId: followee.id,
+				followerId: follower.id,
+			},
 		});
 
-		if (request == null) {
+		if (!requestExist) {
 			throw new IdentifiableError('17447091-ce07-46dd-b331-c1fd4f15b1e7', 'request not found');
 		}
 
diff --git a/packages/backend/src/core/activitypub/ApInboxService.ts b/packages/backend/src/core/activitypub/ApInboxService.ts
index efef777fb..b0428763c 100644
--- a/packages/backend/src/core/activitypub/ApInboxService.ts
+++ b/packages/backend/src/core/activitypub/ApInboxService.ts
@@ -618,12 +618,14 @@ export class ApInboxService {
 			return 'skip: follower not found';
 		}
 
-		const following = await this.followingsRepository.findOneBy({
-			followerId: follower.id,
-			followeeId: actor.id,
+		const isFollowing = await this.followingsRepository.exist({
+			where: {
+				followerId: follower.id,
+				followeeId: actor.id,
+			},
 		});
 
-		if (following) {
+		if (isFollowing) {
 			await this.userFollowingService.unfollow(follower, actor);
 			return 'ok: unfollowed';
 		}
@@ -673,22 +675,26 @@ export class ApInboxService {
 			return 'skip: フォロー解除しようとしているユーザーはローカルユーザーではありません';
 		}
 
-		const req = await this.followRequestsRepository.findOneBy({
-			followerId: actor.id,
-			followeeId: followee.id,
+		const requestExist = await this.followRequestsRepository.exist({
+			where: {
+				followerId: actor.id,
+				followeeId: followee.id,
+			},
 		});
 
-		const following = await this.followingsRepository.findOneBy({
-			followerId: actor.id,
-			followeeId: followee.id,
+		const isFollowing = await this.followingsRepository.exist({
+			where: {
+				followerId: actor.id,
+				followeeId: followee.id,
+			},
 		});
 
-		if (req) {
+		if (requestExist) {
 			await this.userFollowingService.cancelFollowRequest(followee, actor);
 			return 'ok: follow request canceled';
 		}
 
-		if (following) {
+		if (isFollowing) {
 			await this.userFollowingService.unfollow(actor, followee);
 			return 'ok: unfollowed';
 		}
diff --git a/packages/backend/src/core/activitypub/ApRendererService.ts b/packages/backend/src/core/activitypub/ApRendererService.ts
index d8b95ca4d..96ac5c61f 100644
--- a/packages/backend/src/core/activitypub/ApRendererService.ts
+++ b/packages/backend/src/core/activitypub/ApRendererService.ts
@@ -323,9 +323,9 @@ export class ApRendererService {
 			inReplyToNote = await this.notesRepository.findOneBy({ id: note.replyId });
 
 			if (inReplyToNote != null) {
-				const inReplyToUser = await this.usersRepository.findOneBy({ id: inReplyToNote.userId });
+				const inReplyToUserExist = await this.usersRepository.exist({ where: { id: inReplyToNote.userId } });
 
-				if (inReplyToUser != null) {
+				if (inReplyToUserExist) {
 					if (inReplyToNote.uri) {
 						inReplyTo = inReplyToNote.uri;
 					} else {
diff --git a/packages/backend/src/core/entities/ChannelEntityService.ts b/packages/backend/src/core/entities/ChannelEntityService.ts
index 15ffd4486..d24657260 100644
--- a/packages/backend/src/core/entities/ChannelEntityService.ts
+++ b/packages/backend/src/core/entities/ChannelEntityService.ts
@@ -47,17 +47,26 @@ export class ChannelEntityService {
 
 		const banner = channel.bannerId ? await this.driveFilesRepository.findOneBy({ id: channel.bannerId }) : null;
 
-		const hasUnreadNote = meId ? (await this.noteUnreadsRepository.findOneBy({ noteChannelId: channel.id, userId: meId })) != null : undefined;
+		const hasUnreadNote = meId ? await this.noteUnreadsRepository.exist({
+			where: {
+				noteChannelId: channel.id,
+				userId: meId
+			},
+		}) : undefined;
 
-		const following = meId ? await this.channelFollowingsRepository.findOneBy({
-			followerId: meId,
-			followeeId: channel.id,
-		}) : null;
+		const isFollowing = meId ? await this.channelFollowingsRepository.exist({
+			where: {
+				followerId: meId,
+				followeeId: channel.id,
+			},
+		}) : false;
 
-		const favorite = meId ? await this.channelFavoritesRepository.findOneBy({
-			userId: meId,
-			channelId: channel.id,
-		}) : null;
+		const isFavorited = meId ? await this.channelFavoritesRepository.exist({
+			where: {
+				userId: meId,
+				channelId: channel.id,
+			},
+		}) : false;
 
 		const pinnedNotes = channel.pinnedNoteIds.length > 0 ? await this.notesRepository.find({
 			where: {
@@ -80,8 +89,8 @@ export class ChannelEntityService {
 			notesCount: channel.notesCount,
 
 			...(me ? {
-				isFollowing: following != null,
-				isFavorited: favorite != null,
+				isFollowing,
+				isFavorited,
 				hasUnreadNote,
 			} : {}),
 
diff --git a/packages/backend/src/core/entities/ClipEntityService.ts b/packages/backend/src/core/entities/ClipEntityService.ts
index 33d3c5380..f558cbc33 100644
--- a/packages/backend/src/core/entities/ClipEntityService.ts
+++ b/packages/backend/src/core/entities/ClipEntityService.ts
@@ -39,7 +39,7 @@ export class ClipEntityService {
 			description: clip.description,
 			isPublic: clip.isPublic,
 			favoritedCount: await this.clipFavoritesRepository.countBy({ clipId: clip.id }),
-			isFavorited: meId ? await this.clipFavoritesRepository.findOneBy({ clipId: clip.id, userId: meId }).then(x => x != null) : undefined,
+			isFavorited: meId ? await this.clipFavoritesRepository.exist({ where: { clipId: clip.id, userId: meId } }) : undefined,
 		});
 	}
 
diff --git a/packages/backend/src/core/entities/FlashEntityService.ts b/packages/backend/src/core/entities/FlashEntityService.ts
index e52a59188..92345457c 100644
--- a/packages/backend/src/core/entities/FlashEntityService.ts
+++ b/packages/backend/src/core/entities/FlashEntityService.ts
@@ -40,7 +40,7 @@ export class FlashEntityService {
 			summary: flash.summary,
 			script: flash.script,
 			likedCount: flash.likedCount,
-			isLiked: meId ? await this.flashLikesRepository.findOneBy({ flashId: flash.id, userId: meId }).then(x => x != null) : undefined,
+			isLiked: meId ? await this.flashLikesRepository.exist({ where: { flashId: flash.id, userId: meId } }) : undefined,
 		});
 	}
 
diff --git a/packages/backend/src/core/entities/GalleryPostEntityService.ts b/packages/backend/src/core/entities/GalleryPostEntityService.ts
index 632c75304..c44a5df11 100644
--- a/packages/backend/src/core/entities/GalleryPostEntityService.ts
+++ b/packages/backend/src/core/entities/GalleryPostEntityService.ts
@@ -46,7 +46,7 @@ export class GalleryPostEntityService {
 			tags: post.tags.length > 0 ? post.tags : undefined,
 			isSensitive: post.isSensitive,
 			likedCount: post.likedCount,
-			isLiked: meId ? await this.galleryLikesRepository.findOneBy({ postId: post.id, userId: meId }).then(x => x != null) : undefined,
+			isLiked: meId ? await this.galleryLikesRepository.exist({ where: { postId: post.id, userId: meId } }) : undefined,
 		});
 	}
 
diff --git a/packages/backend/src/core/entities/NoteEntityService.ts b/packages/backend/src/core/entities/NoteEntityService.ts
index e730c0eb8..546e5f56d 100644
--- a/packages/backend/src/core/entities/NoteEntityService.ts
+++ b/packages/backend/src/core/entities/NoteEntityService.ts
@@ -106,16 +106,14 @@ export class NoteEntityService implements OnModuleInit {
 				hide = false;
 			} else {
 			// フォロワーかどうか
-				const following = await this.followingsRepository.findOneBy({
-					followeeId: packedNote.userId,
-					followerId: meId,
+				const isFollowing = await this.followingsRepository.exist({
+					where: {
+						followeeId: packedNote.userId,
+						followerId: meId,
+					},
 				});
 
-				if (following == null) {
-					hide = true;
-				} else {
-					hide = false;
-				}
+				hide = !isFollowing;
 			}
 		}
 
diff --git a/packages/backend/src/core/entities/PageEntityService.ts b/packages/backend/src/core/entities/PageEntityService.ts
index d6da85663..94b26a501 100644
--- a/packages/backend/src/core/entities/PageEntityService.ts
+++ b/packages/backend/src/core/entities/PageEntityService.ts
@@ -97,7 +97,7 @@ export class PageEntityService {
 			eyeCatchingImage: page.eyeCatchingImageId ? await this.driveFileEntityService.pack(page.eyeCatchingImageId) : null,
 			attachedFiles: this.driveFileEntityService.packMany((await Promise.all(attachedFiles)).filter((x): x is DriveFile => x != null)),
 			likedCount: page.likedCount,
-			isLiked: meId ? await this.pageLikesRepository.findOneBy({ pageId: page.id, userId: meId }).then(x => x != null) : undefined,
+			isLiked: meId ? await this.pageLikesRepository.exist({ where: { pageId: page.id, userId: meId } }) : undefined,
 		});
 	}
 
diff --git a/packages/backend/src/core/entities/UserEntityService.ts b/packages/backend/src/core/entities/UserEntityService.ts
index 6dacaa103..7d248f852 100644
--- a/packages/backend/src/core/entities/UserEntityService.ts
+++ b/packages/backend/src/core/entities/UserEntityService.ts
@@ -230,12 +230,14 @@ export class UserEntityService implements OnModuleInit {
 		/*
 		const myAntennas = (await this.antennaService.getAntennas()).filter(a => a.userId === userId);
 
-		const unread = myAntennas.length > 0 ? await this.antennaNotesRepository.findOneBy({
-			antennaId: In(myAntennas.map(x => x.id)),
-			read: false,
-		}) : null;
+		const isUnread = (myAntennas.length > 0 ? await this.antennaNotesRepository.exist({
+			where: {
+				antennaId: In(myAntennas.map(x => x.id)),
+				read: false,
+			},
+		}) : false);
 
-		return unread != null;
+		return isUnread;
 		*/
 		return false; // TODO
 	}
diff --git a/packages/backend/src/server/api/SignupApiService.ts b/packages/backend/src/server/api/SignupApiService.ts
index fc5f3811e..5e18dcbe0 100644
--- a/packages/backend/src/server/api/SignupApiService.ts
+++ b/packages/backend/src/server/api/SignupApiService.ts
@@ -128,12 +128,12 @@ export class SignupApiService {
 		}
 
 		if (instance.emailRequiredForSignup) {
-			if (await this.usersRepository.findOneBy({ usernameLower: username.toLowerCase(), host: IsNull() })) {
+			if (await this.usersRepository.exist({ where: { usernameLower: username.toLowerCase(), host: IsNull() } })) {
 				throw new FastifyReplyError(400, 'DUPLICATED_USERNAME');
 			}
 
 			// Check deleted username duplication
-			if (await this.usedUsernamesRepository.findOneBy({ username: username.toLowerCase() })) {
+			if (await this.usedUsernamesRepository.exist({ where: { username: username.toLowerCase() } })) {
 				throw new FastifyReplyError(400, 'USED_USERNAME');
 			}
 
diff --git a/packages/backend/src/server/api/endpoints/admin/promo/create.ts b/packages/backend/src/server/api/endpoints/admin/promo/create.ts
index bee1ffbae..8401cf51d 100644
--- a/packages/backend/src/server/api/endpoints/admin/promo/create.ts
+++ b/packages/backend/src/server/api/endpoints/admin/promo/create.ts
@@ -50,9 +50,9 @@ export default class extends Endpoint<typeof meta, typeof paramDef> {
 				throw e;
 			});
 
-			const exist = await this.promoNotesRepository.findOneBy({ noteId: note.id });
+			const exist = await this.promoNotesRepository.exist({ where: { noteId: note.id } });
 
-			if (exist != null) {
+			if (exist) {
 				throw new ApiError(meta.errors.alreadyPromoted);
 			}
 
diff --git a/packages/backend/src/server/api/endpoints/admin/roles/update.ts b/packages/backend/src/server/api/endpoints/admin/roles/update.ts
index 467f157a6..1fedab454 100644
--- a/packages/backend/src/server/api/endpoints/admin/roles/update.ts
+++ b/packages/backend/src/server/api/endpoints/admin/roles/update.ts
@@ -69,8 +69,8 @@ export default class extends Endpoint<typeof meta, typeof paramDef> {
 		private globalEventService: GlobalEventService,
 	) {
 		super(meta, paramDef, async (ps) => {
-			const role = await this.rolesRepository.findOneBy({ id: ps.roleId });
-			if (role == null) {
+			const roleExist = await this.rolesRepository.exist({ where: { id: ps.roleId } });
+			if (!roleExist) {
 				throw new ApiError(meta.errors.noSuchRole);
 			}
 
diff --git a/packages/backend/src/server/api/endpoints/auth/accept.ts b/packages/backend/src/server/api/endpoints/auth/accept.ts
index e69f9c12e..aa199ab73 100644
--- a/packages/backend/src/server/api/endpoints/auth/accept.ts
+++ b/packages/backend/src/server/api/endpoints/auth/accept.ts
@@ -58,12 +58,14 @@ export default class extends Endpoint<typeof meta, typeof paramDef> {
 			const accessToken = secureRndstr(32);
 
 			// Fetch exist access token
-			const exist = await this.accessTokensRepository.findOneBy({
-				appId: session.appId,
-				userId: me.id,
+			const exist = await this.accessTokensRepository.exist({
+				where: {
+					appId: session.appId,
+					userId: me.id,
+				},
 			});
 
-			if (exist == null) {
+			if (!exist) {
 				const app = await this.appsRepository.findOneByOrFail({ id: session.appId });
 
 				// Generate Hash
diff --git a/packages/backend/src/server/api/endpoints/blocking/create.ts b/packages/backend/src/server/api/endpoints/blocking/create.ts
index d9ba99f20..4ad40c8f1 100644
--- a/packages/backend/src/server/api/endpoints/blocking/create.ts
+++ b/packages/backend/src/server/api/endpoints/blocking/create.ts
@@ -84,12 +84,14 @@ export default class extends Endpoint<typeof meta, typeof paramDef> {
 			});
 
 			// Check if already blocking
-			const exist = await this.blockingsRepository.findOneBy({
-				blockerId: blocker.id,
-				blockeeId: blockee.id,
+			const exist = await this.blockingsRepository.exist({
+				where: {
+					blockerId: blocker.id,
+					blockeeId: blockee.id,
+				},
 			});
 
-			if (exist != null) {
+			if (exist) {
 				throw new ApiError(meta.errors.alreadyBlocking);
 			}
 
diff --git a/packages/backend/src/server/api/endpoints/blocking/delete.ts b/packages/backend/src/server/api/endpoints/blocking/delete.ts
index 46dd26a45..38913ae93 100644
--- a/packages/backend/src/server/api/endpoints/blocking/delete.ts
+++ b/packages/backend/src/server/api/endpoints/blocking/delete.ts
@@ -84,12 +84,14 @@ export default class extends Endpoint<typeof meta, typeof paramDef> {
 			});
 
 			// Check not blocking
-			const exist = await this.blockingsRepository.findOneBy({
-				blockerId: blocker.id,
-				blockeeId: blockee.id,
+			const exist = await this.blockingsRepository.exist({
+				where: {
+					blockerId: blocker.id,
+					blockeeId: blockee.id,
+				}
 			});
 
-			if (exist == null) {
+			if (!exist) {
 				throw new ApiError(meta.errors.notBlocking);
 			}
 
diff --git a/packages/backend/src/server/api/endpoints/clips/add-note.ts b/packages/backend/src/server/api/endpoints/clips/add-note.ts
index c3561e2a7..2837f2cf8 100644
--- a/packages/backend/src/server/api/endpoints/clips/add-note.ts
+++ b/packages/backend/src/server/api/endpoints/clips/add-note.ts
@@ -87,12 +87,14 @@ export default class extends Endpoint<typeof meta, typeof paramDef> {
 				throw e;
 			});
 
-			const exist = await this.clipNotesRepository.findOneBy({
-				noteId: note.id,
-				clipId: clip.id,
+			const exist = await this.clipNotesRepository.exist({
+				where: {
+					noteId: note.id,
+					clipId: clip.id,
+				},
 			});
 
-			if (exist != null) {
+			if (exist) {
 				throw new ApiError(meta.errors.alreadyClipped);
 			}
 
diff --git a/packages/backend/src/server/api/endpoints/clips/favorite.ts b/packages/backend/src/server/api/endpoints/clips/favorite.ts
index f08caaf8d..ce0985553 100644
--- a/packages/backend/src/server/api/endpoints/clips/favorite.ts
+++ b/packages/backend/src/server/api/endpoints/clips/favorite.ts
@@ -58,12 +58,14 @@ export default class extends Endpoint<typeof meta, typeof paramDef> {
 				throw new ApiError(meta.errors.noSuchClip);
 			}
 
-			const exist = await this.clipFavoritesRepository.findOneBy({
-				clipId: clip.id,
-				userId: me.id,
+			const exist = await this.clipFavoritesRepository.exist({
+				where: {
+					clipId: clip.id,
+					userId: me.id,
+				},
 			});
 
-			if (exist != null) {
+			if (exist) {
 				throw new ApiError(meta.errors.alreadyFavorited);
 			}
 
diff --git a/packages/backend/src/server/api/endpoints/drive/files/check-existence.ts b/packages/backend/src/server/api/endpoints/drive/files/check-existence.ts
index 290cd4d2c..cdcdde7e8 100644
--- a/packages/backend/src/server/api/endpoints/drive/files/check-existence.ts
+++ b/packages/backend/src/server/api/endpoints/drive/files/check-existence.ts
@@ -34,12 +34,14 @@ export default class extends Endpoint<typeof meta, typeof paramDef> {
 		private driveFilesRepository: DriveFilesRepository,
 	) {
 		super(meta, paramDef, async (ps, me) => {
-			const file = await this.driveFilesRepository.findOneBy({
-				md5: ps.md5,
-				userId: me.id,
+			const exist = await this.driveFilesRepository.exist({
+				where: {
+					md5: ps.md5,
+					userId: me.id,
+				},
 			});
 
-			return file != null;
+			return exist;
 		});
 	}
 }
diff --git a/packages/backend/src/server/api/endpoints/flash/like.ts b/packages/backend/src/server/api/endpoints/flash/like.ts
index 23de2f397..57245f9f4 100644
--- a/packages/backend/src/server/api/endpoints/flash/like.ts
+++ b/packages/backend/src/server/api/endpoints/flash/like.ts
@@ -66,12 +66,14 @@ export default class extends Endpoint<typeof meta, typeof paramDef> {
 			}
 
 			// if already liked
-			const exist = await this.flashLikesRepository.findOneBy({
-				flashId: flash.id,
-				userId: me.id,
+			const exist = await this.flashLikesRepository.exist({
+				where: {
+					flashId: flash.id,
+					userId: me.id,
+				},
 			});
 
-			if (exist != null) {
+			if (exist) {
 				throw new ApiError(meta.errors.alreadyLiked);
 			}
 
diff --git a/packages/backend/src/server/api/endpoints/following/create.ts b/packages/backend/src/server/api/endpoints/following/create.ts
index 4ad16de91..009fc96f6 100644
--- a/packages/backend/src/server/api/endpoints/following/create.ts
+++ b/packages/backend/src/server/api/endpoints/following/create.ts
@@ -99,12 +99,14 @@ export default class extends Endpoint<typeof meta, typeof paramDef> {
 			});
 
 			// Check if already following
-			const exist = await this.followingsRepository.findOneBy({
-				followerId: follower.id,
-				followeeId: followee.id,
+			const exist = await this.followingsRepository.exist({
+				where: {
+					followerId: follower.id,
+					followeeId: followee.id,
+				},
 			});
 
-			if (exist != null) {
+			if (exist) {
 				throw new ApiError(meta.errors.alreadyFollowing);
 			}
 
diff --git a/packages/backend/src/server/api/endpoints/following/delete.ts b/packages/backend/src/server/api/endpoints/following/delete.ts
index 4f12db127..570c4eb81 100644
--- a/packages/backend/src/server/api/endpoints/following/delete.ts
+++ b/packages/backend/src/server/api/endpoints/following/delete.ts
@@ -84,12 +84,14 @@ export default class extends Endpoint<typeof meta, typeof paramDef> {
 			});
 
 			// Check not following
-			const exist = await this.followingsRepository.findOneBy({
-				followerId: follower.id,
-				followeeId: followee.id,
+			const exist = await this.followingsRepository.exist({
+				where: {
+					followerId: follower.id,
+					followeeId: followee.id,
+				},
 			});
 
-			if (exist == null) {
+			if (!exist) {
 				throw new ApiError(meta.errors.notFollowing);
 			}
 
diff --git a/packages/backend/src/server/api/endpoints/gallery/posts/like.ts b/packages/backend/src/server/api/endpoints/gallery/posts/like.ts
index 6ac5fa860..c0bb55f64 100644
--- a/packages/backend/src/server/api/endpoints/gallery/posts/like.ts
+++ b/packages/backend/src/server/api/endpoints/gallery/posts/like.ts
@@ -66,12 +66,14 @@ export default class extends Endpoint<typeof meta, typeof paramDef> {
 			}
 
 			// if already liked
-			const exist = await this.galleryLikesRepository.findOneBy({
-				postId: post.id,
-				userId: me.id,
+			const exist = await this.galleryLikesRepository.exist({
+				where: {
+					postId: post.id,
+					userId: me.id,
+				},
 			});
 
-			if (exist != null) {
+			if (exist) {
 				throw new ApiError(meta.errors.alreadyLiked);
 			}
 
diff --git a/packages/backend/src/server/api/endpoints/i/import-antennas.ts b/packages/backend/src/server/api/endpoints/i/import-antennas.ts
index 12ec5855d..8582e98f7 100644
--- a/packages/backend/src/server/api/endpoints/i/import-antennas.ts
+++ b/packages/backend/src/server/api/endpoints/i/import-antennas.ts
@@ -66,8 +66,8 @@ export default class extends Endpoint<typeof meta, typeof paramDef> {
 		private downloadService: DownloadService,
 	) {
 		super(meta, paramDef, async (ps, me) => {
-			const users = await this.usersRepository.findOneBy({ id: me.id });
-			if (users === null) throw new ApiError(meta.errors.noSuchUser);
+			const userExist = await this.usersRepository.exist({ where: { id: me.id } });
+			if (!userExist) throw new ApiError(meta.errors.noSuchUser);
 			const file = await this.driveFilesRepository.findOneBy({ id: ps.fileId });
 			if (file === null) throw new ApiError(meta.errors.noSuchFile);
 			if (file.size === 0) throw new ApiError(meta.errors.emptyFile);
diff --git a/packages/backend/src/server/api/endpoints/i/read-announcement.ts b/packages/backend/src/server/api/endpoints/i/read-announcement.ts
index b8922b91e..352fe54c5 100644
--- a/packages/backend/src/server/api/endpoints/i/read-announcement.ts
+++ b/packages/backend/src/server/api/endpoints/i/read-announcement.ts
@@ -47,19 +47,21 @@ export default class extends Endpoint<typeof meta, typeof paramDef> {
 	) {
 		super(meta, paramDef, async (ps, me) => {
 			// Check if announcement exists
-			const announcement = await this.announcementsRepository.findOneBy({ id: ps.announcementId });
+			const announcementExist = await this.announcementsRepository.exist({ where: { id: ps.announcementId } });
 
-			if (announcement == null) {
+			if (!announcementExist) {
 				throw new ApiError(meta.errors.noSuchAnnouncement);
 			}
 
 			// Check if already read
-			const read = await this.announcementReadsRepository.findOneBy({
-				announcementId: ps.announcementId,
-				userId: me.id,
+			const alreadyRead = await this.announcementReadsRepository.exist({
+				where: {
+					announcementId: ps.announcementId,
+					userId: me.id,
+				},
 			});
 
-			if (read != null) {
+			if (alreadyRead) {
 				return;
 			}
 
diff --git a/packages/backend/src/server/api/endpoints/i/revoke-token.ts b/packages/backend/src/server/api/endpoints/i/revoke-token.ts
index 93daeb0cd..415a60147 100644
--- a/packages/backend/src/server/api/endpoints/i/revoke-token.ts
+++ b/packages/backend/src/server/api/endpoints/i/revoke-token.ts
@@ -28,9 +28,9 @@ export default class extends Endpoint<typeof meta, typeof paramDef> {
 		private globalEventService: GlobalEventService,
 	) {
 		super(meta, paramDef, async (ps, me) => {
-			const token = await this.accessTokensRepository.findOneBy({ id: ps.tokenId });
+			const tokenExist = await this.accessTokensRepository.exist({ where: { id: ps.tokenId } });
 
-			if (token) {
+			if (tokenExist) {
 				await this.accessTokensRepository.delete({
 					id: ps.tokenId,
 					userId: me.id,
diff --git a/packages/backend/src/server/api/endpoints/mute/create.ts b/packages/backend/src/server/api/endpoints/mute/create.ts
index ee358d5c6..ef53f9ef4 100644
--- a/packages/backend/src/server/api/endpoints/mute/create.ts
+++ b/packages/backend/src/server/api/endpoints/mute/create.ts
@@ -79,12 +79,14 @@ export default class extends Endpoint<typeof meta, typeof paramDef> {
 			});
 
 			// Check if already muting
-			const exist = await this.mutingsRepository.findOneBy({
-				muterId: muter.id,
-				muteeId: mutee.id,
+			const exist = await this.mutingsRepository.exist({
+				where: {
+					muterId: muter.id,
+					muteeId: mutee.id,
+				},
 			});
 
-			if (exist != null) {
+			if (exist) {
 				throw new ApiError(meta.errors.alreadyMuting);
 			}
 
diff --git a/packages/backend/src/server/api/endpoints/notes/create.ts b/packages/backend/src/server/api/endpoints/notes/create.ts
index 96be5ed84..739316997 100644
--- a/packages/backend/src/server/api/endpoints/notes/create.ts
+++ b/packages/backend/src/server/api/endpoints/notes/create.ts
@@ -217,11 +217,13 @@ export default class extends Endpoint<typeof meta, typeof paramDef> {
 
 				// Check blocking
 				if (renote.userId !== me.id) {
-					const block = await this.blockingsRepository.findOneBy({
-						blockerId: renote.userId,
-						blockeeId: me.id,
+					const blockExist = await this.blockingsRepository.exist({
+						where: {
+							blockerId: renote.userId,
+							blockeeId: me.id,
+						},
 					});
-					if (block) {
+					if (blockExist) {
 						throw new ApiError(meta.errors.youHaveBeenBlocked);
 					}
 				}
@@ -240,11 +242,13 @@ export default class extends Endpoint<typeof meta, typeof paramDef> {
 
 				// Check blocking
 				if (reply.userId !== me.id) {
-					const block = await this.blockingsRepository.findOneBy({
-						blockerId: reply.userId,
-						blockeeId: me.id,
+					const blockExist = await this.blockingsRepository.exist({
+						where: {
+							blockerId: reply.userId,
+							blockeeId: me.id,
+						},
 					});
-					if (block) {
+					if (blockExist) {
 						throw new ApiError(meta.errors.youHaveBeenBlocked);
 					}
 				}
diff --git a/packages/backend/src/server/api/endpoints/notes/favorites/create.ts b/packages/backend/src/server/api/endpoints/notes/favorites/create.ts
index 611ea1956..9299d6603 100644
--- a/packages/backend/src/server/api/endpoints/notes/favorites/create.ts
+++ b/packages/backend/src/server/api/endpoints/notes/favorites/create.ts
@@ -63,12 +63,14 @@ export default class extends Endpoint<typeof meta, typeof paramDef> {
 			});
 
 			// if already favorited
-			const exist = await this.noteFavoritesRepository.findOneBy({
-				noteId: note.id,
-				userId: me.id,
+			const exist = await this.noteFavoritesRepository.exist({
+				where: {
+					noteId: note.id,
+					userId: me.id,
+				},
 			});
 
-			if (exist != null) {
+			if (exist) {
 				throw new ApiError(meta.errors.alreadyFavorited);
 			}
 
diff --git a/packages/backend/src/server/api/endpoints/pages/like.ts b/packages/backend/src/server/api/endpoints/pages/like.ts
index 543c126d9..bc6648810 100644
--- a/packages/backend/src/server/api/endpoints/pages/like.ts
+++ b/packages/backend/src/server/api/endpoints/pages/like.ts
@@ -66,12 +66,14 @@ export default class extends Endpoint<typeof meta, typeof paramDef> {
 			}
 
 			// if already liked
-			const exist = await this.pageLikesRepository.findOneBy({
-				pageId: page.id,
-				userId: me.id,
+			const exist = await this.pageLikesRepository.exist({
+				where: {
+					pageId: page.id,
+					userId: me.id,
+				},
 			});
 
-			if (exist != null) {
+			if (exist) {
 				throw new ApiError(meta.errors.alreadyLiked);
 			}
 
diff --git a/packages/backend/src/server/api/endpoints/promo/read.ts b/packages/backend/src/server/api/endpoints/promo/read.ts
index 90febdbce..9baa930f5 100644
--- a/packages/backend/src/server/api/endpoints/promo/read.ts
+++ b/packages/backend/src/server/api/endpoints/promo/read.ts
@@ -44,12 +44,14 @@ export default class extends Endpoint<typeof meta, typeof paramDef> {
 				throw err;
 			});
 
-			const exist = await this.promoReadsRepository.findOneBy({
-				noteId: note.id,
-				userId: me.id,
+			const exist = await this.promoReadsRepository.exist({
+				where: {
+					noteId: note.id,
+					userId: me.id,
+				},
 			});
 
-			if (exist != null) {
+			if (exist) {
 				return;
 			}
 
diff --git a/packages/backend/src/server/api/endpoints/users/followers.ts b/packages/backend/src/server/api/endpoints/users/followers.ts
index c6f71474b..18d66500a 100644
--- a/packages/backend/src/server/api/endpoints/users/followers.ts
+++ b/packages/backend/src/server/api/endpoints/users/followers.ts
@@ -97,11 +97,13 @@ export default class extends Endpoint<typeof meta, typeof paramDef> {
 				if (me == null) {
 					throw new ApiError(meta.errors.forbidden);
 				} else if (me.id !== user.id) {
-					const following = await this.followingsRepository.findOneBy({
-						followeeId: user.id,
-						followerId: me.id,
+					const isFollowing = await this.followingsRepository.exist({
+						where: {
+							followeeId: user.id,
+							followerId: me.id,
+						},
 					});
-					if (following == null) {
+					if (!isFollowing) {
 						throw new ApiError(meta.errors.forbidden);
 					}
 				}
diff --git a/packages/backend/src/server/api/endpoints/users/following.ts b/packages/backend/src/server/api/endpoints/users/following.ts
index b072c9662..6ea7b923d 100644
--- a/packages/backend/src/server/api/endpoints/users/following.ts
+++ b/packages/backend/src/server/api/endpoints/users/following.ts
@@ -97,11 +97,13 @@ export default class extends Endpoint<typeof meta, typeof paramDef> {
 				if (me == null) {
 					throw new ApiError(meta.errors.forbidden);
 				} else if (me.id !== user.id) {
-					const following = await this.followingsRepository.findOneBy({
-						followeeId: user.id,
-						followerId: me.id,
+					const isFollowing = await this.followingsRepository.exist({
+						where: {
+							followeeId: user.id,
+							followerId: me.id,
+						},
 					});
-					if (following == null) {
+					if (!isFollowing) {
 						throw new ApiError(meta.errors.forbidden);
 					}
 				}
diff --git a/packages/backend/src/server/api/endpoints/users/lists/create-from-public.ts b/packages/backend/src/server/api/endpoints/users/lists/create-from-public.ts
index cccffcdad..beb0ba85f 100644
--- a/packages/backend/src/server/api/endpoints/users/lists/create-from-public.ts
+++ b/packages/backend/src/server/api/endpoints/users/lists/create-from-public.ts
@@ -84,11 +84,13 @@ export default class extends Endpoint<typeof meta, typeof paramDef> {
 		private roleService: RoleService,
 	) {
 		super(meta, paramDef, async (ps, me) => {
-			const list = await this.userListsRepository.findOneBy({
-				id: ps.listId,
-				isPublic: true,
+			const listExist = await this.userListsRepository.exist({
+				where: {
+					id: ps.listId,
+					isPublic: true,
+				},
 			});
-			if (list === null) throw new ApiError(meta.errors.noSuchList);
+			if (!listExist) throw new ApiError(meta.errors.noSuchList);
 			const currentCount = await this.userListsRepository.countBy({
 				userId: me.id,
 			});
@@ -114,18 +116,22 @@ export default class extends Endpoint<typeof meta, typeof paramDef> {
 				});
 
 				if (currentUser.id !== me.id) {
-					const block = await this.blockingsRepository.findOneBy({
-						blockerId: currentUser.id,
-						blockeeId: me.id,
+					const blockExist = await this.blockingsRepository.exist({
+						where: {
+							blockerId: currentUser.id,
+							blockeeId: me.id,
+						},
 					});
-					if (block) {
+					if (blockExist) {
 						throw new ApiError(meta.errors.youHaveBeenBlocked);
 					}
 				}
 
-				const exist = await this.userListJoiningsRepository.findOneBy({
-					userListId: userList.id,
-					userId: currentUser.id,
+				const exist = await this.userListJoiningsRepository.exist({
+					where: {
+						userListId: userList.id,
+						userId: currentUser.id,
+					},
 				});
 
 				if (exist) {
diff --git a/packages/backend/src/server/api/endpoints/users/lists/favorite.ts b/packages/backend/src/server/api/endpoints/users/lists/favorite.ts
index ea1a022be..2c09a47fe 100644
--- a/packages/backend/src/server/api/endpoints/users/lists/favorite.ts
+++ b/packages/backend/src/server/api/endpoints/users/lists/favorite.ts
@@ -41,21 +41,25 @@ export default class extends Endpoint<typeof meta, typeof paramDef> {
 		private idService: IdService,
 	) {
 		super(meta, paramDef, async (ps, me) => {
-			const userList = await this.userListsRepository.findOneBy({
-				id: ps.listId,
-				isPublic: true,
+			const userListExist = await this.userListsRepository.exist({
+				where: {
+					id: ps.listId,
+					isPublic: true,
+				},
 			});
 
-			if (userList === null) {
+			if (!userListExist) {
 				throw new ApiError(meta.errors.noSuchList);
 			}
 
-			const exist = await this.userListFavoritesRepository.findOneBy({
-				userId: me.id,
-				userListId: ps.listId,
+			const exist = await this.userListFavoritesRepository.exist({
+				where: {
+					userId: me.id,
+					userListId: ps.listId,
+				},
 			});
 
-			if (exist !== null) {
+			if (exist) {
 				throw new ApiError(meta.errors.alreadyFavorited);
 			}
 
diff --git a/packages/backend/src/server/api/endpoints/users/lists/push.ts b/packages/backend/src/server/api/endpoints/users/lists/push.ts
index 925037e48..6e1f6b2c6 100644
--- a/packages/backend/src/server/api/endpoints/users/lists/push.ts
+++ b/packages/backend/src/server/api/endpoints/users/lists/push.ts
@@ -100,18 +100,22 @@ export default class extends Endpoint<typeof meta, typeof paramDef> {
 
 			// Check blocking
 			if (user.id !== me.id) {
-				const block = await this.blockingsRepository.findOneBy({
-					blockerId: user.id,
-					blockeeId: me.id,
+				const blockExist = await this.blockingsRepository.exist({
+					where: {
+						blockerId: user.id,
+						blockeeId: me.id,
+					},
 				});
-				if (block) {
+				if (blockExist) {
 					throw new ApiError(meta.errors.youHaveBeenBlocked);
 				}
 			}
 
-			const exist = await this.userListJoiningsRepository.findOneBy({
-				userListId: userList.id,
-				userId: user.id,
+			const exist = await this.userListJoiningsRepository.exist({
+				where: {
+					userListId: userList.id,
+					userId: user.id,
+				},
 			});
 
 			if (exist) {
diff --git a/packages/backend/src/server/api/endpoints/users/lists/show.ts b/packages/backend/src/server/api/endpoints/users/lists/show.ts
index 8077841c8..3fd418d04 100644
--- a/packages/backend/src/server/api/endpoints/users/lists/show.ts
+++ b/packages/backend/src/server/api/endpoints/users/lists/show.ts
@@ -69,10 +69,12 @@ export default class extends Endpoint<typeof meta, typeof paramDef> {
 					userListId: ps.listId,
 				});
 				if (me !== null) {
-					additionalProperties.isLiked = (await this.userListFavoritesRepository.findOneBy({
-						userId: me.id,
-						userListId: ps.listId,
-					}) !== null);
+					additionalProperties.isLiked = await this.userListFavoritesRepository.exist({
+						where: {
+							userId: me.id,
+							userListId: ps.listId,
+						},
+					});
 				} else {
 					additionalProperties.isLiked = false;
 				}
diff --git a/packages/backend/src/server/api/endpoints/users/lists/unfavorite.ts b/packages/backend/src/server/api/endpoints/users/lists/unfavorite.ts
index be8e31781..a7c3b5894 100644
--- a/packages/backend/src/server/api/endpoints/users/lists/unfavorite.ts
+++ b/packages/backend/src/server/api/endpoints/users/lists/unfavorite.ts
@@ -39,12 +39,14 @@ export default class extends Endpoint<typeof meta, typeof paramDef> {
 		private userListFavoritesRepository: UserListFavoritesRepository,
 	) {
 		super(meta, paramDef, async (ps, me) => {
-			const userList = await this.userListsRepository.findOneBy({
-				id: ps.listId,
-				isPublic: true,
+			const userListExist = await this.userListsRepository.exist({
+				where: {
+					id: ps.listId,
+					isPublic: true,
+				},
 			});
 
-			if (userList === null) {
+			if (!userListExist) {
 				throw new ApiError(meta.errors.noSuchList);
 			}
 
diff --git a/packages/backend/src/server/api/stream/channels/user-list.ts b/packages/backend/src/server/api/stream/channels/user-list.ts
index d97d2b8ba..ea4cff0bc 100644
--- a/packages/backend/src/server/api/stream/channels/user-list.ts
+++ b/packages/backend/src/server/api/stream/channels/user-list.ts
@@ -34,11 +34,13 @@ class UserListChannel extends Channel {
 		this.listId = params.listId as string;
 
 		// Check existence and owner
-		const list = await this.userListsRepository.findOneBy({
-			id: this.listId,
-			userId: this.user!.id,
+		const listExist = await this.userListsRepository.exist({
+			where: {
+				id: this.listId,
+				userId: this.user!.id,
+			},
 		});
-		if (!list) return;
+		if (!listExist) return;
 
 		// Subscribe stream
 		this.subscriber.on(`userListStream:${this.listId}`, this.send);