diff --git a/packages/backend/assets/emoji-unknown.png b/packages/backend/assets/emoji-unknown.png
new file mode 100644
index 0000000000..ab29bef2b1
Binary files /dev/null and b/packages/backend/assets/emoji-unknown.png differ
diff --git a/packages/backend/src/server/ServerService.ts b/packages/backend/src/server/ServerService.ts
index beb26e43d1..fac8497b5e 100644
--- a/packages/backend/src/server/ServerService.ts
+++ b/packages/backend/src/server/ServerService.ts
@@ -1,12 +1,11 @@
 import cluster from 'node:cluster';
 import * as fs from 'node:fs';
-import * as http from 'node:http';
 import { Inject, Injectable } from '@nestjs/common';
 import Fastify from 'fastify';
 import { IsNull } from 'typeorm';
 import { GlobalEventService } from '@/core/GlobalEventService.js';
 import type { Config } from '@/config.js';
-import type { UserProfilesRepository, UsersRepository } from '@/models/index.js';
+import type { EmojisRepository, UserProfilesRepository, UsersRepository } from '@/models/index.js';
 import { DI } from '@/di-symbols.js';
 import type Logger from '@/logger.js';
 import { envOption } from '@/env.js';
@@ -39,6 +38,9 @@ export class ServerService {
 		@Inject(DI.userProfilesRepository)
 		private userProfilesRepository: UserProfilesRepository,
 
+		@Inject(DI.emojisRepository)
+		private emojisRepository: EmojisRepository,
+
 		private userEntityService: UserEntityService,
 		private apiServerService: ApiServerService,
 		private streamingApiServerService: StreamingApiServerService,
@@ -77,6 +79,43 @@ export class ServerService {
 		fastify.register(this.nodeinfoServerService.createServer);
 		fastify.register(this.wellKnownServerService.createServer);
 
+		fastify.get<{ Params: { path: string }; Querystring: { static?: any; }; }>('/emoji/:path(.*)', async (request, reply) => {
+			const path = request.params.path;
+
+			if (!path.match(/^[a-zA-Z0-9\-_@\.]+?\.webp$/)) {
+				reply.code(404);
+				return;
+			}
+
+			reply.header('Cache-Control', 'public, max-age=86400');
+
+			const name = path.split('@')[0].replace('.webp', '');
+			const host = path.split('@')[1]?.replace('.webp', '');
+
+			const emoji = await this.emojisRepository.findOneBy({
+				// `@.` is the spec of ReactionService.decodeReaction
+				host: (host == null || host === '.') ? IsNull() : host,
+				name: name,
+			});
+
+			reply.header('Content-Security-Policy', 'default-src \'none\'; style-src \'unsafe-inline\'');
+
+			if (emoji == null) {
+				return await reply.redirect('/static-assets/emoji-unknown.png');
+			}
+
+			const url = new URL('/proxy/emoji.webp', this.config.url);
+			// || emoji.originalUrl してるのは後方互換性のため（publicUrlはstringなので??はだめ）
+			url.searchParams.set('url', emoji.publicUrl || emoji.originalUrl);
+			url.searchParams.set('emoji', '1');
+			if ('static' in request.query) url.searchParams.set('static', '1');
+
+			return await reply.redirect(
+				301,
+				url.toString(),
+			);
+		});
+
 		fastify.get<{ Params: { acct: string } }>('/avatar/@:acct', async (request, reply) => {
 			const { username, host } = Acct.parse(request.params.acct);
 			const user = await this.usersRepository.findOne({
diff --git a/packages/backend/src/server/web/ClientServerService.ts b/packages/backend/src/server/web/ClientServerService.ts
index a7701e1b24..c69975fd79 100644
--- a/packages/backend/src/server/web/ClientServerService.ts
+++ b/packages/backend/src/server/web/ClientServerService.ts
@@ -1,6 +1,5 @@
 import { dirname } from 'node:path';
 import { fileURLToPath } from 'node:url';
-import { PathOrFileDescriptor, readFileSync } from 'node:fs';
 import { Inject, Injectable } from '@nestjs/common';
 import { createBullBoard } from '@bull-board/api';
 import { BullAdapter } from '@bull-board/api/bullAdapter.js';
@@ -71,9 +70,6 @@ export class ClientServerService {
 		@Inject(DI.pagesRepository)
 		private pagesRepository: PagesRepository,
 
-		@Inject(DI.emojisRepository)
-		private emojisRepository: EmojisRepository,
-
 		@Inject(DI.flashsRepository)
 		private flashsRepository: FlashsRepository,
 
@@ -225,44 +221,6 @@ export class ClientServerService {
 			return reply.sendFile('/apple-touch-icon.png', staticAssets);
 		});
 
-		fastify.get<{ Params: { path: string }; Querystring: { static?: any; }; }>('/emoji/:path(.*)', async (request, reply) => {
-			const path = request.params.path;
-
-			if (!path.match(/^[a-zA-Z0-9\-_@\.]+?\.webp$/)) {
-				reply.code(404);
-				return;
-			}
-
-			reply.header('Cache-Control', 'public, max-age=86400');
-
-			const name = path.split('@')[0].replace('.webp', '');
-			const host = path.split('@')[1]?.replace('.webp', '');
-
-			const emoji = await this.emojisRepository.findOneBy({
-				// `@.` is the spec of ReactionService.decodeReaction
-				host: (host == null || host === '.') ? IsNull() : host,
-				name: name,
-			});
-
-			if (emoji == null) {
-				reply.code(404);
-				return;
-			}
-
-			reply.header('Content-Security-Policy', 'default-src \'none\'; style-src \'unsafe-inline\'');
-
-			const url = new URL('/proxy/emoji.webp', this.config.url);
-			// || emoji.originalUrl してるのは後方互換性のため（publicUrlはstringなので??はだめ）
-			url.searchParams.set('url', emoji.publicUrl || emoji.originalUrl);
-			url.searchParams.set('emoji', '1');
-			if ('static' in request.query) url.searchParams.set('static', '1');
-
-			return await reply.redirect(
-				301,
-				url.toString(),
-			);
-		});
-
 		fastify.get<{ Params: { path: string } }>('/fluent-emoji/:path(.*)', async (request, reply) => {
 			const path = request.params.path;