diff --git a/packages/backend/src/misc/i18n.ts b/packages/backend/src/misc/i18n.ts
index 4fa398763..25f059bb6 100644
--- a/packages/backend/src/misc/i18n.ts
+++ b/packages/backend/src/misc/i18n.ts
@@ -1,19 +1,18 @@
-export class I18n<T extends Record<string, any>> {
-	public locale: T;
+const locales = import('../../../../locales/index.js').then(mod => mod.default);
 
-	constructor(locale: T) {
-		this.locale = locale;
+export class I18n {
+	public ts: Record<string, any>;
 
-		//#region BIND
+	constructor(locale: string) {
+		this.ts = locales[locale];
 		this.t = this.t.bind(this);
-		//#endregion
 	}
 
 	// string にしているのは、ドット区切りでのパス指定を許可するため
 	// なるべくこのメソッド使うよりもlocale直接参照の方がvueのキャッシュ効いてパフォーマンスが良いかも
 	public t(key: string, args?: Record<string, any>): string {
 		try {
-			let str = key.split('.').reduce((o, i) => o[i], this.locale) as string;
+			let str = key.split('.').reduce((o, i) => o[i], this.ts) as string;
 
 			if (args) {
 				for (const [k, v] of Object.entries(args)) {
diff --git a/packages/backend/src/server/api/service/discord.ts b/packages/backend/src/server/api/service/discord.ts
index 2f6e9fb01..c9b8e03b9 100644
--- a/packages/backend/src/server/api/service/discord.ts
+++ b/packages/backend/src/server/api/service/discord.ts
@@ -27,8 +27,6 @@ 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();
 
@@ -50,8 +48,7 @@ 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);
+	const i18n = new I18n(profile.lang ?? 'en-US');
 
 	delete profile.integrations.discord;
 
@@ -264,8 +261,7 @@ 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);
+		const i18n = new I18n(profile.lang ?? 'en-US');
 
 		await UserProfiles.update(user.id, {
 			integrations: {
diff --git a/packages/backend/src/server/api/service/github.ts b/packages/backend/src/server/api/service/github.ts
index da4716bc3..5e78130e7 100644
--- a/packages/backend/src/server/api/service/github.ts
+++ b/packages/backend/src/server/api/service/github.ts
@@ -27,8 +27,6 @@ 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();
 
@@ -50,8 +48,7 @@ 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);
+	const i18n = new I18n(profile.lang ?? 'en-US');
 
 	delete profile.integrations.github;
 
@@ -239,8 +236,7 @@ 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);
+		const i18n = new I18n(profile.lang ?? 'en-US');
 
 		await UserProfiles.update(user.id, {
 			integrations: {
diff --git a/packages/backend/src/server/api/service/twitter.ts b/packages/backend/src/server/api/service/twitter.ts
index 309bd922e..59da0f6ba 100644
--- a/packages/backend/src/server/api/service/twitter.ts
+++ b/packages/backend/src/server/api/service/twitter.ts
@@ -26,8 +26,6 @@ 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();
 
@@ -49,8 +47,7 @@ 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);
+	const i18n = new I18n(profile.lang ?? 'en-US');
 
 	delete profile.integrations.twitter;
 
@@ -180,8 +177,7 @@ 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);
+		const i18n = new I18n(profile.lang ?? 'en-US');
 
 		await UserProfiles.update(user.id, {
 			integrations: {
diff --git a/packages/backend/src/services/send-email-notification.ts b/packages/backend/src/services/send-email-notification.ts
index 740eacfe6..cd3c670ac 100644
--- a/packages/backend/src/services/send-email-notification.ts
+++ b/packages/backend/src/services/send-email-notification.ts
@@ -3,8 +3,6 @@ import { User } from '@/models/entities/user.js';
 import { I18n } from '@/misc/i18n.js';
 import * as Acct from '@/misc/acct.js';
 import { sendEmail } from './send-email.js';
-// TODO
-//const locales = await import('../../../../locales/index.js');
 
 // TODO: locale ファイルをクライアント用とサーバー用で分けたい
 
@@ -12,8 +10,7 @@ async function follow(userId: User['id'], follower: User) {
 	/*
 	const userProfile = await UserProfiles.findOneByOrFail({ userId: userId });
 	if (!userProfile.email || !userProfile.emailNotificationTypes.includes('follow')) return;
-	const locale = locales[userProfile.lang || 'en-US'];
-	const i18n = new I18n(locale);
+	const i18n = new I18n(userProfile.lang ?? 'en-US');
 	// TODO: render user information html
 	sendEmail(userProfile.email, i18n.t('_email._follow.title'), `${follower.name} (@${Acct.toString(follower)})`, `${follower.name} (@${Acct.toString(follower)})`);
 	*/
@@ -23,8 +20,7 @@ async function receiveFollowRequest(userId: User['id'], follower: User) {
 	/*
 	const userProfile = await UserProfiles.findOneByOrFail({ userId: userId });
 	if (!userProfile.email || !userProfile.emailNotificationTypes.includes('receiveFollowRequest')) return;
-	const locale = locales[userProfile.lang || 'en-US'];
-	const i18n = new I18n(locale);
+	const i18n = new I18n(userProfile.lang ?? 'en-US');
 	// TODO: render user information html
 	sendEmail(userProfile.email, i18n.t('_email._receiveFollowRequest.title'), `${follower.name} (@${Acct.toString(follower)})`, `${follower.name} (@${Acct.toString(follower)})`);
 	*/