diff --git a/packages/backend/src/remote/activitypub/models/person.ts b/packages/backend/src/remote/activitypub/models/person.ts
index c5519ba03..14abf3b1d 100644
--- a/packages/backend/src/remote/activitypub/models/person.ts
+++ b/packages/backend/src/remote/activitypub/models/person.ts
@@ -147,11 +147,11 @@ export async function fetchPerson(
 	}
 
 	//#region Returns if already registered with this server
-	const exist = await Users.findOneBy({ uri });
+	const user = await Users.findOneBy({ uri });
 
-	if (exist) {
-		await uriPersonCache.set(uri, exist);
-		return exist;
+	if (user != null) {
+		await uriPersonCache.set(uri, user);
+		return user;
 	}
 	//#endregion
 
@@ -396,9 +396,9 @@ export async function updatePerson(
 	}
 
 	//#region Already registered on this server?
-	const exist = (await Users.findOneBy({ uri })) as IRemoteUser;
+	const user = (await Users.findOneBy({ uri })) as IRemoteUser;
 
-	if (exist == null) {
+	if (user == null) {
 		return;
 	}
 	//#endregion
@@ -416,17 +416,15 @@ export async function updatePerson(
 		[person.icon, person.image].map((img) =>
 			img == null
 				? Promise.resolve(null)
-				: resolveImage(exist, img).catch(() => null),
+				: resolveImage(user, img).catch(() => null),
 		),
 	);
 
 	// Custom pictogram acquisition
-	const emojis = await extractEmojis(person.tag || [], exist.host).catch(
-		(e) => {
-			logger.info(`extractEmojis: ${e}`);
-			return [] as Emoji[];
-		},
-	);
+	const emojis = await extractEmojis(person.tag || [], user.host).catch((e) => {
+		logger.info(`extractEmojis: ${e}`);
+		return [] as Emoji[];
+	});
 
 	const emojiNames = emojis.map((emoji) => emoji.name);
 
@@ -518,11 +516,11 @@ export async function updatePerson(
 	}
 
 	// Update user
-	await Users.update(exist.id, updates);
+	await Users.update(user.id, updates);
 
 	if (person.publicKey) {
 		await UserPublickeys.update(
-			{ userId: exist.id },
+			{ userId: user.id },
 			{
 				keyId: person.publicKey.id,
 				keyPem: person.publicKey.publicKeyPem,
@@ -531,7 +529,7 @@ export async function updatePerson(
 	}
 
 	await UserProfiles.update(
-		{ userId: exist.id },
+		{ userId: user.id },
 		{
 			url: url,
 			fields,
@@ -543,15 +541,15 @@ export async function updatePerson(
 		},
 	);
 
-	publishInternalEvent("remoteUserUpdated", { id: exist.id });
+	publishInternalEvent("remoteUserUpdated", { id: user.id });
 
 	// Hashtag Update
-	updateUsertags(exist, tags);
+	updateUsertags(user, tags);
 
 	// If the user in question is a follower, followers will also be updated.
 	await Followings.update(
 		{
-			followerId: exist.id,
+			followerId: user.id,
 		},
 		{
 			followerSharedInbox:
@@ -560,7 +558,7 @@ export async function updatePerson(
 		},
 	);
 
-	await updateFeatured(exist.id, resolver).catch((err) => logger.error(err));
+	await updateFeatured(user.id, resolver).catch((err) => logger.error(err));
 }
 
 /**
@@ -576,10 +574,10 @@ export async function resolvePerson(
 	if (typeof uri !== "string") throw new Error("uri is not string");
 
 	//#region If already registered on this server, return it.
-	const exist = await fetchPerson(uri);
+	const user = await fetchPerson(uri);
 
-	if (exist) {
-		return exist;
+	if (user != null) {
+		return user;
 	}
 	//#endregion
 
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 a6d1f3519..00244a777 100644
--- a/packages/backend/src/server/api/endpoints/admin/promo/create.ts
+++ b/packages/backend/src/server/api/endpoints/admin/promo/create.ts
@@ -40,9 +40,9 @@ export default define(meta, paramDef, async (ps, user) => {
 		throw err;
 	});
 
-	const exist = await PromoNotes.findOneBy({ noteId: note.id });
+	const exist = await PromoNotes.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/auth/accept.ts b/packages/backend/src/server/api/endpoints/auth/accept.ts
index 35565e256..8e6ad6527 100644
--- a/packages/backend/src/server/api/endpoints/auth/accept.ts
+++ b/packages/backend/src/server/api/endpoints/auth/accept.ts
@@ -41,12 +41,14 @@ export default define(meta, paramDef, async (ps, user) => {
 	const accessToken = secureRndstr(32, true);
 
 	// Fetch exist access token
-	const exist = await AccessTokens.findOneBy({
-		appId: session.appId,
-		userId: user.id,
+	const exist = await AccessTokens.exist({
+		where: {
+			appId: session.appId,
+			userId: user.id,
+		},
 	});
 
-	if (exist == null) {
+	if (!exist) {
 		// Lookup app
 		const app = await Apps.findOneByOrFail({ id: session.appId });
 
diff --git a/packages/backend/src/server/api/endpoints/blocking/create.ts b/packages/backend/src/server/api/endpoints/blocking/create.ts
index 4bd58d5ef..f00a2923d 100644
--- a/packages/backend/src/server/api/endpoints/blocking/create.ts
+++ b/packages/backend/src/server/api/endpoints/blocking/create.ts
@@ -69,12 +69,14 @@ export default define(meta, paramDef, async (ps, user) => {
 	});
 
 	// Check if already blocking
-	const exist = await Blockings.findOneBy({
-		blockerId: blocker.id,
-		blockeeId: blockee.id,
+	const exist = await Blockings.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 6c4ca2775..037d5af22 100644
--- a/packages/backend/src/server/api/endpoints/blocking/delete.ts
+++ b/packages/backend/src/server/api/endpoints/blocking/delete.ts
@@ -69,12 +69,14 @@ export default define(meta, paramDef, async (ps, user) => {
 	});
 
 	// Check not blocking
-	const exist = await Blockings.findOneBy({
-		blockerId: blocker.id,
-		blockeeId: blockee.id,
+	const exist = await Blockings.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 b9d6b54c9..416af6faa 100644
--- a/packages/backend/src/server/api/endpoints/clips/add-note.ts
+++ b/packages/backend/src/server/api/endpoints/clips/add-note.ts
@@ -57,12 +57,14 @@ export default define(meta, paramDef, async (ps, user) => {
 		throw err;
 	});
 
-	const exist = await ClipNotes.findOneBy({
-		noteId: note.id,
-		clipId: clip.id,
+	const exist = await ClipNotes.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/drive/files/check-existence.ts b/packages/backend/src/server/api/endpoints/drive/files/check-existence.ts
index df8968520..e26da30eb 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
@@ -26,10 +26,12 @@ export const paramDef = {
 } as const;
 
 export default define(meta, paramDef, async (ps, user) => {
-	const file = await DriveFiles.findOneBy({
-		md5: ps.md5,
-		userId: user.id,
+	const exist = await DriveFiles.exist({
+		where: {
+			md5: ps.md5,
+			userId: user.id,
+		},
 	});
 
-	return file != null;
+	return exist;
 });
diff --git a/packages/backend/src/server/api/endpoints/following/create.ts b/packages/backend/src/server/api/endpoints/following/create.ts
index e617c1ffb..48ae6ae7a 100644
--- a/packages/backend/src/server/api/endpoints/following/create.ts
+++ b/packages/backend/src/server/api/endpoints/following/create.ts
@@ -82,12 +82,14 @@ export default define(meta, paramDef, async (ps, user) => {
 	});
 
 	// Check if already following
-	const exist = await Followings.findOneBy({
-		followerId: follower.id,
-		followeeId: followee.id,
+	const exist = await Followings.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 2eebe8a90..cbc6097f4 100644
--- a/packages/backend/src/server/api/endpoints/following/delete.ts
+++ b/packages/backend/src/server/api/endpoints/following/delete.ts
@@ -69,12 +69,14 @@ export default define(meta, paramDef, async (ps, user) => {
 	});
 
 	// Check not following
-	const exist = await Followings.findOneBy({
-		followerId: follower.id,
-		followeeId: followee.id,
+	const exist = await Followings.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/following/invalidate.ts b/packages/backend/src/server/api/endpoints/following/invalidate.ts
index 979d298f7..01ccc2761 100644
--- a/packages/backend/src/server/api/endpoints/following/invalidate.ts
+++ b/packages/backend/src/server/api/endpoints/following/invalidate.ts
@@ -69,12 +69,14 @@ export default define(meta, paramDef, async (ps, user) => {
 	});
 
 	// Check not following
-	const exist = await Followings.findOneBy({
-		followerId: follower.id,
-		followeeId: followee.id,
+	const exist = await Followings.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 fd46406bd..2506e40aa 100644
--- a/packages/backend/src/server/api/endpoints/gallery/posts/like.ts
+++ b/packages/backend/src/server/api/endpoints/gallery/posts/like.ts
@@ -40,12 +40,14 @@ export default define(meta, paramDef, async (ps, user) => {
 	}
 
 	// if already liked
-	const exist = await GalleryLikes.findOneBy({
-		postId: post.id,
-		userId: user.id,
+	const exist = await GalleryLikes.exist({
+		where: {
+			postId: post.id,
+			userId: user.id,
+		},
 	});
 
-	if (exist != null) {
+	if (exist) {
 		throw new ApiError(meta.errors.alreadyLiked);
 	}
 
diff --git a/packages/backend/src/server/api/endpoints/gallery/posts/unlike.ts b/packages/backend/src/server/api/endpoints/gallery/posts/unlike.ts
index 772dc9202..03bc299b9 100644
--- a/packages/backend/src/server/api/endpoints/gallery/posts/unlike.ts
+++ b/packages/backend/src/server/api/endpoints/gallery/posts/unlike.ts
@@ -38,17 +38,17 @@ export default define(meta, paramDef, async (ps, user) => {
 		throw new ApiError(meta.errors.noSuchPost);
 	}
 
-	const exist = await GalleryLikes.findOneBy({
+	const like = await GalleryLikes.findOneBy({
 		postId: post.id,
 		userId: user.id,
 	});
 
-	if (exist == null) {
+	if (like == null) {
 		throw new ApiError(meta.errors.notLiked);
 	}
 
 	// Delete like
-	await GalleryLikes.delete(exist.id);
+	await GalleryLikes.delete(like.id);
 
 	GalleryPosts.decrement({ id: post.id }, "likedCount", 1);
 });
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 5218dba87..d0dfa6657 100644
--- a/packages/backend/src/server/api/endpoints/i/read-announcement.ts
+++ b/packages/backend/src/server/api/endpoints/i/read-announcement.ts
@@ -30,19 +30,23 @@ export const paramDef = {
 
 export default define(meta, paramDef, async (ps, user) => {
 	// Check if announcement exists
-	const announcement = await Announcements.findOneBy({ id: ps.announcementId });
+	const exist = await Announcements.exist({
+		where: { id: ps.announcementId },
+	});
 
-	if (announcement == null) {
+	if (!exist) {
 		throw new ApiError(meta.errors.noSuchAnnouncement);
 	}
 
 	// Check if already read
-	const read = await AnnouncementReads.findOneBy({
-		announcementId: ps.announcementId,
-		userId: user.id,
+	const read = await AnnouncementReads.exist({
+		where: {
+			announcementId: ps.announcementId,
+			userId: user.id,
+		},
 	});
 
-	if (read != null) {
+	if (read) {
 		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 308442bf7..3a410fa0e 100644
--- a/packages/backend/src/server/api/endpoints/i/revoke-token.ts
+++ b/packages/backend/src/server/api/endpoints/i/revoke-token.ts
@@ -17,9 +17,9 @@ export const paramDef = {
 } as const;
 
 export default define(meta, paramDef, async (ps, user) => {
-	const token = await AccessTokens.findOneBy({ id: ps.tokenId });
+	const exist = await AccessTokens.exist({ where: { id: ps.tokenId } });
 
-	if (token) {
+	if (exist) {
 		await AccessTokens.delete({
 			id: ps.tokenId,
 			userId: user.id,
diff --git a/packages/backend/src/server/api/endpoints/mute/create.ts b/packages/backend/src/server/api/endpoints/mute/create.ts
index bacab9b45..7b2f10905 100644
--- a/packages/backend/src/server/api/endpoints/mute/create.ts
+++ b/packages/backend/src/server/api/endpoints/mute/create.ts
@@ -64,12 +64,14 @@ export default define(meta, paramDef, async (ps, user) => {
 	});
 
 	// Check if already muting
-	const exist = await Mutings.findOneBy({
-		muterId: muter.id,
-		muteeId: mutee.id,
+	const exist = await Mutings.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/mute/delete.ts b/packages/backend/src/server/api/endpoints/mute/delete.ts
index cc67a44c2..cd00c1a8a 100644
--- a/packages/backend/src/server/api/endpoints/mute/delete.ts
+++ b/packages/backend/src/server/api/endpoints/mute/delete.ts
@@ -56,18 +56,18 @@ export default define(meta, paramDef, async (ps, user) => {
 	});
 
 	// Check not muting
-	const exist = await Mutings.findOneBy({
+	const muting = await Mutings.findOneBy({
 		muterId: muter.id,
 		muteeId: mutee.id,
 	});
 
-	if (exist == null) {
+	if (muting == null) {
 		throw new ApiError(meta.errors.notMuting);
 	}
 
 	// Delete mute
 	await Mutings.delete({
-		id: exist.id,
+		id: muting.id,
 	});
 
 	publishUserEvent(user.id, "unmute", mutee);
diff --git a/packages/backend/src/server/api/endpoints/notes/create.ts b/packages/backend/src/server/api/endpoints/notes/create.ts
index 41b8ab979..e15221046 100644
--- a/packages/backend/src/server/api/endpoints/notes/create.ts
+++ b/packages/backend/src/server/api/endpoints/notes/create.ts
@@ -224,11 +224,13 @@ export default define(meta, paramDef, async (ps, user) => {
 
 		// Check blocking
 		if (renote.userId !== user.id) {
-			const block = await Blockings.findOneBy({
-				blockerId: renote.userId,
-				blockeeId: user.id,
+			const isBlocked = await Blockings.exist({
+				where: {
+					blockerId: renote.userId,
+					blockeeId: user.id,
+				},
 			});
-			if (block) {
+			if (isBlocked) {
 				throw new ApiError(meta.errors.youHaveBeenBlocked);
 			}
 		}
@@ -249,11 +251,13 @@ export default define(meta, paramDef, async (ps, user) => {
 
 		// Check blocking
 		if (reply.userId !== user.id) {
-			const block = await Blockings.findOneBy({
-				blockerId: reply.userId,
-				blockeeId: user.id,
+			const isBlocked = await Blockings.exist({
+				where: {
+					blockerId: reply.userId,
+					blockeeId: user.id,
+				},
 			});
-			if (block) {
+			if (isBlocked) {
 				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 835594f03..64862a373 100644
--- a/packages/backend/src/server/api/endpoints/notes/favorites/create.ts
+++ b/packages/backend/src/server/api/endpoints/notes/favorites/create.ts
@@ -43,12 +43,14 @@ export default define(meta, paramDef, async (ps, user) => {
 	});
 
 	// if already favorited
-	const exist = await NoteFavorites.findOneBy({
-		noteId: note.id,
-		userId: user.id,
+	const exist = await NoteFavorites.exist({
+		where: {
+			noteId: note.id,
+			userId: user.id,
+		},
 	});
 
-	if (exist != null) {
+	if (exist) {
 		throw new ApiError(meta.errors.alreadyFavorited);
 	}
 
diff --git a/packages/backend/src/server/api/endpoints/notes/favorites/delete.ts b/packages/backend/src/server/api/endpoints/notes/favorites/delete.ts
index 9a0976748..e05d04a96 100644
--- a/packages/backend/src/server/api/endpoints/notes/favorites/delete.ts
+++ b/packages/backend/src/server/api/endpoints/notes/favorites/delete.ts
@@ -42,15 +42,15 @@ export default define(meta, paramDef, async (ps, user) => {
 	});
 
 	// if already favorited
-	const exist = await NoteFavorites.findOneBy({
+	const favorite = await NoteFavorites.findOneBy({
 		noteId: note.id,
 		userId: user.id,
 	});
 
-	if (exist == null) {
+	if (favorite == null) {
 		throw new ApiError(meta.errors.notFavorited);
 	}
 
 	// Delete favorite
-	await NoteFavorites.delete(exist.id);
+	await NoteFavorites.delete(favorite.id);
 });
diff --git a/packages/backend/src/server/api/endpoints/pages/like.ts b/packages/backend/src/server/api/endpoints/pages/like.ts
index f14ed39eb..03482c961 100644
--- a/packages/backend/src/server/api/endpoints/pages/like.ts
+++ b/packages/backend/src/server/api/endpoints/pages/like.ts
@@ -40,12 +40,14 @@ export default define(meta, paramDef, async (ps, user) => {
 	}
 
 	// if already liked
-	const exist = await PageLikes.findOneBy({
-		pageId: page.id,
-		userId: user.id,
+	const exist = await PageLikes.exist({
+		where: {
+			pageId: page.id,
+			userId: user.id,
+		},
 	});
 
-	if (exist != null) {
+	if (exist) {
 		throw new ApiError(meta.errors.alreadyLiked);
 	}
 
diff --git a/packages/backend/src/server/api/endpoints/pages/unlike.ts b/packages/backend/src/server/api/endpoints/pages/unlike.ts
index 07bf3fbf4..e607d7a54 100644
--- a/packages/backend/src/server/api/endpoints/pages/unlike.ts
+++ b/packages/backend/src/server/api/endpoints/pages/unlike.ts
@@ -38,17 +38,17 @@ export default define(meta, paramDef, async (ps, user) => {
 		throw new ApiError(meta.errors.noSuchPage);
 	}
 
-	const exist = await PageLikes.findOneBy({
+	const like = await PageLikes.findOneBy({
 		pageId: page.id,
 		userId: user.id,
 	});
 
-	if (exist == null) {
+	if (like == null) {
 		throw new ApiError(meta.errors.notLiked);
 	}
 
 	// Delete like
-	await PageLikes.delete(exist.id);
+	await PageLikes.delete(like.id);
 
 	Pages.decrement({ id: page.id }, "likedCount", 1);
 });
diff --git a/packages/backend/src/server/api/endpoints/promo/read.ts b/packages/backend/src/server/api/endpoints/promo/read.ts
index 09c8cb6fa..5310382a4 100644
--- a/packages/backend/src/server/api/endpoints/promo/read.ts
+++ b/packages/backend/src/server/api/endpoints/promo/read.ts
@@ -33,12 +33,14 @@ export default define(meta, paramDef, async (ps, user) => {
 		throw err;
 	});
 
-	const exist = await PromoReads.findOneBy({
-		noteId: note.id,
-		userId: user.id,
+	const exist = await PromoReads.exist({
+		where: {
+			noteId: note.id,
+			userId: user.id,
+		},
 	});
 
-	if (exist != null) {
+	if (exist) {
 		return;
 	}
 
diff --git a/packages/backend/src/server/api/endpoints/renote-mute/create.ts b/packages/backend/src/server/api/endpoints/renote-mute/create.ts
index 857cbd975..f09f197c0 100644
--- a/packages/backend/src/server/api/endpoints/renote-mute/create.ts
+++ b/packages/backend/src/server/api/endpoints/renote-mute/create.ts
@@ -47,12 +47,14 @@ export default define(meta, paramDef, async (ps, user) => {
 	});
 
 	// Check if already muting
-	const exist = await RenoteMutings.findOneBy({
-		muterId: muter.id,
-		muteeId: mutee.id,
+	const exist = await RenoteMutings.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/renote-mute/delete.ts b/packages/backend/src/server/api/endpoints/renote-mute/delete.ts
index fb4c972af..7a898141c 100644
--- a/packages/backend/src/server/api/endpoints/renote-mute/delete.ts
+++ b/packages/backend/src/server/api/endpoints/renote-mute/delete.ts
@@ -45,18 +45,18 @@ export default define(meta, paramDef, async (ps, user) => {
 	});
 
 	// Check not muting
-	const exist = await RenoteMutings.findOneBy({
+	const muting = await RenoteMutings.findOneBy({
 		muterId: muter.id,
 		muteeId: mutee.id,
 	});
 
-	if (exist == null) {
+	if (muting == null) {
 		throw new ApiError(meta.errors.notMuting);
 	}
 
 	// Delete mute
 	await RenoteMutings.delete({
-		id: exist.id,
+		id: muting.id,
 	});
 
 	// publishUserEvent(user.id, "unmute", mutee);
diff --git a/packages/backend/src/server/api/endpoints/sw/register.ts b/packages/backend/src/server/api/endpoints/sw/register.ts
index 41be4bf74..6268ae26d 100644
--- a/packages/backend/src/server/api/endpoints/sw/register.ts
+++ b/packages/backend/src/server/api/endpoints/sw/register.ts
@@ -57,8 +57,7 @@ export const paramDef = {
 } as const;
 
 export default define(meta, paramDef, async (ps, me) => {
-	// if already subscribed
-	const exist = await SwSubscriptions.findOneBy({
+	const subscription = await SwSubscriptions.findOneBy({
 		userId: me.id,
 		endpoint: ps.endpoint,
 		auth: ps.auth,
@@ -67,13 +66,14 @@ export default define(meta, paramDef, async (ps, me) => {
 
 	const instance = await fetchMeta(true);
 
-	if (exist != null) {
+	// if already subscribed
+	if (subscription != null) {
 		return {
 			state: "already-subscribed" as const,
 			key: instance.swPublicKey,
 			userId: me.id,
-			endpoint: exist.endpoint,
-			sendReadMessage: exist.sendReadMessage,
+			endpoint: subscription.endpoint,
+			sendReadMessage: subscription.sendReadMessage,
 		};
 	}
 
diff --git a/packages/backend/src/server/api/endpoints/sw/show-registration.ts b/packages/backend/src/server/api/endpoints/sw/show-registration.ts
index c7a9609cf..3ccb7de94 100644
--- a/packages/backend/src/server/api/endpoints/sw/show-registration.ts
+++ b/packages/backend/src/server/api/endpoints/sw/show-registration.ts
@@ -42,16 +42,16 @@ export const paramDef = {
 
 // eslint-disable-next-line import/no-default-export
 export default define(meta, paramDef, async (ps, me) => {
-	const exist = await SwSubscriptions.findOneBy({
+	const subscription = await SwSubscriptions.findOneBy({
 		userId: me.id,
 		endpoint: ps.endpoint,
 	});
 
-	if (exist != null) {
+	if (subscription != null) {
 		return {
-			userId: exist.userId,
-			endpoint: exist.endpoint,
-			sendReadMessage: exist.sendReadMessage,
+			userId: subscription.userId,
+			endpoint: subscription.endpoint,
+			sendReadMessage: subscription.sendReadMessage,
 		};
 	}
 
diff --git a/packages/backend/src/server/api/endpoints/users/followers.ts b/packages/backend/src/server/api/endpoints/users/followers.ts
index 855ab3573..31719bad3 100644
--- a/packages/backend/src/server/api/endpoints/users/followers.ts
+++ b/packages/backend/src/server/api/endpoints/users/followers.ts
@@ -98,11 +98,13 @@ export default define(meta, paramDef, async (ps, me) => {
 		if (me == null) {
 			throw new ApiError(meta.errors.forbidden);
 		} else if (me.id !== user.id) {
-			const following = await Followings.findOneBy({
-				followeeId: user.id,
-				followerId: me.id,
+			const isFollowed = await Followings.exist({
+				where: {
+					followeeId: user.id,
+					followerId: me.id,
+				},
 			});
-			if (following == null) {
+			if (!isFollowed) {
 				throw new ApiError(meta.errors.nullFollowers);
 			}
 		}
diff --git a/packages/backend/src/server/api/endpoints/users/following.ts b/packages/backend/src/server/api/endpoints/users/following.ts
index 37d69b048..1c1da0e11 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 define(meta, paramDef, async (ps, me) => {
 		if (me == null) {
 			throw new ApiError(meta.errors.forbidden);
 		} else if (me.id !== user.id) {
-			const following = await Followings.findOneBy({
-				followeeId: user.id,
-				followerId: me.id,
+			const isFollowing = await Followings.exist({
+				where: {
+					followeeId: user.id,
+					followerId: me.id,
+				},
 			});
-			if (following == null) {
+			if (!isFollowing) {
 				throw new ApiError(meta.errors.cannot_find);
 			}
 		}
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 a14195bbc..6f3e09fcb 100644
--- a/packages/backend/src/server/api/endpoints/users/lists/push.ts
+++ b/packages/backend/src/server/api/endpoints/users/lists/push.ts
@@ -52,12 +52,14 @@ export const paramDef = {
 
 export default define(meta, paramDef, async (ps, me) => {
 	// Fetch the list
-	const userList = await UserLists.findOneBy({
-		id: ps.listId,
-		userId: me.id,
+	const listExists = await UserLists.exist({
+		where: {
+			id: ps.listId,
+			userId: me.id,
+		},
 	});
 
-	if (userList == null) {
+	if (!listExists) {
 		throw new ApiError(meta.errors.noSuchList);
 	}
 
@@ -70,18 +72,22 @@ export default define(meta, paramDef, async (ps, me) => {
 
 	// Check blocking
 	if (user.id !== me.id) {
-		const block = await Blockings.findOneBy({
-			blockerId: user.id,
-			blockeeId: me.id,
+		const isBlocked = await Blockings.exist({
+			where: {
+				blockerId: user.id,
+				blockeeId: me.id,
+			},
 		});
-		if (block) {
+		if (isBlocked) {
 			throw new ApiError(meta.errors.youHaveBeenBlocked);
 		}
 	}
 
-	const exist = await UserListJoinings.findOneBy({
-		userListId: userList.id,
-		userId: user.id,
+	const exist = await UserListJoinings.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 716fd405d..8479a4e03 100644
--- a/packages/backend/src/server/api/endpoints/users/lists/show.ts
+++ b/packages/backend/src/server/api/endpoints/users/lists/show.ts
@@ -37,12 +37,14 @@ export const paramDef = {
 
 export default define(meta, paramDef, async (ps, me) => {
 	// Fetch the list
-	const userList = await UserLists.findOneBy({
-		id: ps.listId,
-		userId: me.id,
+	const exist = await UserLists.exist({
+		where: {
+			id: ps.listId,
+			userId: me.id,
+		},
 	});
 
-	if (userList == null) {
+	if (!exist) {
 		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 0b52f6912..d14031950 100644
--- a/packages/backend/src/server/api/stream/channels/user-list.ts
+++ b/packages/backend/src/server/api/stream/channels/user-list.ts
@@ -22,11 +22,13 @@ export default class extends Channel {
 		this.listId = params.listId as string;
 
 		// Check existence and owner
-		const list = await UserLists.findOneBy({
-			id: this.listId,
-			userId: this.user!.id,
+		const exist = await UserLists.exist({
+			where: {
+				id: this.listId,
+				userId: this.user!.id,
+			},
 		});
-		if (!list) return;
+		if (!exist) return;
 
 		// Subscribe stream
 		this.subscriber.on(`userListStream:${this.listId}`, this.send);
diff --git a/packages/backend/src/services/note/reaction/delete.ts b/packages/backend/src/services/note/reaction/delete.ts
index 82648249e..15c6d1cf6 100644
--- a/packages/backend/src/services/note/reaction/delete.ts
+++ b/packages/backend/src/services/note/reaction/delete.ts
@@ -13,13 +13,13 @@ export default async (
 	user: { id: User["id"]; host: User["host"] },
 	note: Note,
 ) => {
-	// if already unreacted
-	const exist = await NoteReactions.findOneBy({
+	const reaction = await NoteReactions.findOneBy({
 		noteId: note.id,
 		userId: user.id,
 	});
 
-	if (exist == null) {
+	// if already unreacted
+	if (reaction == null) {
 		throw new IdentifiableError(
 			"60527ec9-b4cb-4a88-a6bd-32d3ad26817d",
 			"not reacted",
@@ -27,7 +27,7 @@ export default async (
 	}
 
 	// Delete reaction
-	const result = await NoteReactions.delete(exist.id);
+	const result = await NoteReactions.delete(reaction.id);
 
 	if (result.affected !== 1) {
 		throw new IdentifiableError(
@@ -37,7 +37,7 @@ export default async (
 	}
 
 	// Decrement reactions count
-	const sql = `jsonb_set("reactions", '{${exist.reaction}}', (COALESCE("reactions"->>'${exist.reaction}', '0')::int - 1)::text::jsonb)`;
+	const sql = `jsonb_set("reactions", '{${reaction.reaction}}', (COALESCE("reactions"->>'${reaction.reaction}', '0')::int - 1)::text::jsonb)`;
 	await Notes.createQueryBuilder()
 		.update()
 		.set({
@@ -49,14 +49,14 @@ export default async (
 	Notes.decrement({ id: note.id }, "score", 1);
 
 	publishNoteStream(note.id, "unreacted", {
-		reaction: decodeReaction(exist.reaction).reaction,
+		reaction: decodeReaction(reaction.reaction).reaction,
 		userId: user.id,
 	});
 
 	//#region 配信
 	if (Users.isLocalUser(user) && !note.localOnly) {
 		const content = renderActivity(
-			renderUndo(await renderLike(exist, note), user),
+			renderUndo(await renderLike(reaction, note), user),
 		);
 		const dm = new DeliverManager(user, content);
 		if (note.userHost !== null) {
diff --git a/packages/backend/src/services/note/unread.ts b/packages/backend/src/services/note/unread.ts
index 275b230d4..cb87abe0e 100644
--- a/packages/backend/src/services/note/unread.ts
+++ b/packages/backend/src/services/note/unread.ts
@@ -42,9 +42,9 @@ export async function insertNoteUnread(
 
 	// 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(async () => {
-		const exist = await NoteUnreads.findOneBy({ id: unread.id });
+		const exist = await NoteUnreads.exist({ where: { id: unread.id } });
 
-		if (exist == null) return;
+		if (!exist) return;
 
 		if (params.isMentioned) {
 			publishMainStream(userId, "unreadMention", note.id);