diff --git a/locales/en-US.yml b/locales/en-US.yml
index 3187acba8..83a8485b4 100644
--- a/locales/en-US.yml
+++ b/locales/en-US.yml
@@ -1409,3 +1409,13 @@ _deck:
     list: "List"
     mentions: "Mentions"
     direct: "Direct notes"
+_services:
+  _discord:
+    connected: "Discord: @{username}#{discriminator} connected to FoundKey: @{mkUsername}!"
+    disconnected: "Discord linkage has been removed :v:"
+  _twitter:
+    connected: "Twitter: @{twitterUserName} connected to FoundKey: @{userName}!"
+    disconnected: "Twitter linkage has been removed :v:"
+  _github:
+    connected: "GitHub: @{login} connected to FoundKey: @{userName}!"
+    disconnected: "GitHub linkage has been removed :v:"
diff --git a/locales/ja-JP.yml b/locales/ja-JP.yml
index 4f37a67e7..8a6d40d5d 100644
--- a/locales/ja-JP.yml
+++ b/locales/ja-JP.yml
@@ -1452,3 +1452,13 @@ _deck:
     list: "リスト"
     mentions: "あなた宛て"
     direct: "ダイレクト"
+_services:
+  _discord:
+    connected: "Discord: @{username}#{discriminator} を、FoundKey: @{mkUsername} に接続しました！"
+    disconnected: "Discordの連携を解除しました :v:"
+  _twitter:
+    connected: "Twitter: @{twitterUserName} を、FoundKey: @{userName} に接続しました！"
+    disconnected: "Twitterの連携を解除しました :v:"
+  _github:
+    connected: "GitHub: @{login} を、FoundKey: @{userName} に接続しました！"
+    disconnected: "GitHubの連携を解除しました :v:"
diff --git a/packages/backend/src/server/api/service/discord.ts b/packages/backend/src/server/api/service/discord.ts
index 9d0cc47f4..2f6e9fb01 100644
--- a/packages/backend/src/server/api/service/discord.ts
+++ b/packages/backend/src/server/api/service/discord.ts
@@ -10,6 +10,7 @@ import { fetchMeta } from '@/misc/fetch-meta.js';
 import { Users, UserProfiles } from '@/models/index.js';
 import { ILocalUser } from '@/models/entities/user.js';
 import { redisClient } from '@/db/redis.js';
+import { I18n } from '@/misc/i18n.js';
 import signin from '../common/signin.js';
 
 function getUserToken(ctx: Koa.BaseContext): string | null {
@@ -26,6 +27,8 @@ function compareOrigin(ctx: Koa.BaseContext): boolean {
 	return (normalizeUrl(referer) === normalizeUrl(config.url));
 }
 
+const locales = await import('../../../../../../locales/index.js').then(mod => mod.default);
+
 // Init router
 const router = new Router();
 
@@ -47,6 +50,8 @@ router.get('/disconnect/discord', async ctx => {
 	});
 
 	const profile = await UserProfiles.findOneByOrFail({ userId: user.id });
+	const locale = locales[profile.lang || 'en-US'];
+	const i18n = new I18n(locale);
 
 	delete profile.integrations.discord;
 
@@ -54,7 +59,7 @@ router.get('/disconnect/discord', async ctx => {
 		integrations: profile.integrations,
 	});
 
-	ctx.body = 'Discordの連携を解除しました :v:';
+	ctx.body = i18n.t('_services._discord.disconnected');
 
 	// Publish i updated event
 	publishMainStream(user.id, 'meUpdated', await Users.pack(user, user, {
@@ -259,6 +264,8 @@ router.get('/dc/cb', async ctx => {
 		});
 
 		const profile = await UserProfiles.findOneByOrFail({ userId: user.id });
+		const locale = locales[profile.lang || 'en-US'];
+		const i18n = new I18n(locale);
 
 		await UserProfiles.update(user.id, {
 			integrations: {
@@ -274,7 +281,11 @@ router.get('/dc/cb', async ctx => {
 			},
 		});
 
-		ctx.body = `Discord: @${username}#${discriminator} connected to FoundKey: @${user.username}!`;
+		ctx.body = i18n.t('_services._discord.connected', {
+			username,
+			discriminator,
+			mkUsername: user.username,
+		});
 
 		// Publish i updated event
 		publishMainStream(user.id, 'meUpdated', await Users.pack(user, user, {
diff --git a/packages/backend/src/server/api/service/github.ts b/packages/backend/src/server/api/service/github.ts
index 640bbf82c..da4716bc3 100644
--- a/packages/backend/src/server/api/service/github.ts
+++ b/packages/backend/src/server/api/service/github.ts
@@ -11,6 +11,7 @@ import { Users, UserProfiles } from '@/models/index.js';
 import { ILocalUser } from '@/models/entities/user.js';
 import { redisClient } from '@/db/redis.js';
 import signin from '../common/signin.js';
+import { I18n } from '@/misc/i18n.js';
 
 function getUserToken(ctx: Koa.BaseContext): string | null {
 	return ((ctx.headers['cookie'] || '').match(/igi=(\w+)/) || [null, null])[1];
@@ -26,6 +27,8 @@ function compareOrigin(ctx: Koa.BaseContext): boolean {
 	return (normalizeUrl(referer) === normalizeUrl(config.url));
 }
 
+const locales = await import('../../../../../../locales/index.js').then(mod => mod.default);
+
 // Init router
 const router = new Router();
 
@@ -47,6 +50,8 @@ router.get('/disconnect/github', async ctx => {
 	});
 
 	const profile = await UserProfiles.findOneByOrFail({ userId: user.id });
+	const locale = locales[profile.lang || 'en-US'];
+	const i18n = new I18n(locale);
 
 	delete profile.integrations.github;
 
@@ -54,7 +59,7 @@ router.get('/disconnect/github', async ctx => {
 		integrations: profile.integrations,
 	});
 
-	ctx.body = 'GitHubの連携を解除しました :v:';
+	ctx.body = i18n.t('_services._github.disconnected');
 
 	// Publish i updated event
 	publishMainStream(user.id, 'meUpdated', await Users.pack(user, user, {
@@ -234,6 +239,8 @@ router.get('/gh/cb', async ctx => {
 		});
 
 		const profile = await UserProfiles.findOneByOrFail({ userId: user.id });
+		const locale = locales[profile.lang || 'en-US'];
+		const i18n = new I18n(locale);
 
 		await UserProfiles.update(user.id, {
 			integrations: {
@@ -246,7 +253,10 @@ router.get('/gh/cb', async ctx => {
 			},
 		});
 
-		ctx.body = `GitHub: @${login} connected to FoundKey: @${user.username}!`;
+		ctx.body = i18n.t('_services._github.connected', {
+			login,
+			userName: user.username,
+		});
 
 		// Publish i updated event
 		publishMainStream(user.id, 'meUpdated', await Users.pack(user, user, {
diff --git a/packages/backend/src/server/api/service/twitter.ts b/packages/backend/src/server/api/service/twitter.ts
index 5594206f1..309bd922e 100644
--- a/packages/backend/src/server/api/service/twitter.ts
+++ b/packages/backend/src/server/api/service/twitter.ts
@@ -10,6 +10,7 @@ import { Users, UserProfiles } from '@/models/index.js';
 import { ILocalUser } from '@/models/entities/user.js';
 import { redisClient } from '@/db/redis.js';
 import signin from '../common/signin.js';
+import { I18n } from '@/misc/i18n.js';
 
 function getUserToken(ctx: Koa.BaseContext): string | null {
 	return ((ctx.headers['cookie'] || '').match(/igi=(\w+)/) || [null, null])[1];
@@ -25,6 +26,8 @@ function compareOrigin(ctx: Koa.BaseContext): boolean {
 	return (normalizeUrl(referer) === normalizeUrl(config.url));
 }
 
+const locales = await import('../../../../../../locales/index.js').then(mod => mod.default);
+
 // Init router
 const router = new Router();
 
@@ -46,6 +49,8 @@ router.get('/disconnect/twitter', async ctx => {
 	});
 
 	const profile = await UserProfiles.findOneByOrFail({ userId: user.id });
+	const locale = locales[profile.lang || 'en-US'];
+	const i18n = new I18n(locale);
 
 	delete profile.integrations.twitter;
 
@@ -53,7 +58,7 @@ router.get('/disconnect/twitter', async ctx => {
 		integrations: profile.integrations,
 	});
 
-	ctx.body = 'Twitter linkage has been removed :v:';
+	ctx.body = i18n.t('_services._twitter.disconnected');
 
 	// Publish i updated event
 	publishMainStream(user.id, 'meUpdated', await Users.pack(user, user, {
@@ -175,6 +180,8 @@ router.get('/tw/cb', async ctx => {
 		});
 
 		const profile = await UserProfiles.findOneByOrFail({ userId: user.id });
+		const locale = locales[profile.lang || 'en-US'];
+		const i18n = new I18n(locale);
 
 		await UserProfiles.update(user.id, {
 			integrations: {
@@ -188,7 +195,10 @@ router.get('/tw/cb', async ctx => {
 			},
 		});
 
-		ctx.body = `Twitter: @${result.screenName} connected to FoundKey: @${user.username}!`;
+		ctx.body = i18n.t('_services._twitter.connected', {
+			twitterUserName: result.screenName,
+			userName: user.username,
+		});
 
 		// Publish i updated event
 		publishMainStream(user.id, 'meUpdated', await Users.pack(user, user, {
diff --git a/packages/backend/tsconfig.json b/packages/backend/tsconfig.json
index 0702607e3..6e17dad7a 100644
--- a/packages/backend/tsconfig.json
+++ b/packages/backend/tsconfig.json
@@ -10,8 +10,8 @@
 		"noFallthroughCasesInSwitch": true,
 		"declaration": false,
 		"sourceMap": false,
-		"target": "es2017",
-		"module": "es2020",
+		"target": "ES2021",
+		"module": "esnext",
 		"moduleResolution": "node",
 		"allowSyntheticDefaultImports": true,
 		"removeComments": false,