diff --git a/assets/data/toolsNav.ts b/assets/data/toolsNav.ts
index ae47aef4..1601d657 100644
--- a/assets/data/toolsNav.ts
+++ b/assets/data/toolsNav.ts
@@ -15,9 +15,9 @@ export default <NavSection[]>[
                 to: "/tools/avatar-decoration-preview/",
             },
             {
-                i18n: "_aidConverter.title",
-                description: "_aidConverter.description",
-                to: "/tools/aid-converter/",
+                i18n: "_customEmojiPreview.title",
+                description: "_customEmojiPreview.description",
+                to: "/tools/custom-emoji-preview/",
             },
             {
                 i18n: "_shareLinkGenerator.title",
@@ -26,4 +26,14 @@ export default <NavSection[]>[
             },
         ],
     },
+    {
+        title: "_tools._forAdmin.title",
+        items: [
+            {
+                i18n: "_aidConverter.title",
+                description: "_aidConverter.description",
+                to: "/tools/aid-converter/",
+            },
+        ],
+    }
 ];
\ No newline at end of file
diff --git a/components/mk/CustomEmoji.vue b/components/mk/CustomEmoji.vue
index 585aa15a..aaf5fd54 100644
--- a/components/mk/CustomEmoji.vue
+++ b/components/mk/CustomEmoji.vue
@@ -38,6 +38,10 @@ const rawUrl = computed(() => {
 const url = computed(() => {
 	if (rawUrl.value == null) return null;
 
+    if (props.url) {
+        return rawUrl.value;
+    }
+
 	const proxied =
 		(rawUrl.value.startsWith('/emoji/') || (props.useOriginalSize && isLocal.value))
 			? parseURL(rawUrl.value).host ? rawUrl.value : 'https://misskey.io' + rawUrl.value
@@ -51,7 +55,7 @@ const url = computed(() => {
 });
 
 const alt = computed(() => `:${customEmojiName.value}:`);
-const errored = ref(props.host == null);
+const errored = ref(props.host == null && !props.url);
 </script>
 
 <style lang="scss" module>
diff --git a/components/mk/Mfm.ts b/components/mk/Mfm.ts
index 6b3a4b9c..09ed908b 100644
--- a/components/mk/Mfm.ts
+++ b/components/mk/Mfm.ts
@@ -31,6 +31,8 @@ export default function(props: {
 	rootScale?: number;
 	/** 表示の基準にするMisskeyサーバーのドメイン */
 	baseHost?: string;
+	/** 差し込むカスタム絵文字（:key:と画像URL） */
+	customEmojis?: Record<string, string>;
 }) {
 	const isNote = props.isNote !== undefined ? props.isNote : true;
 
@@ -281,7 +283,15 @@ export default function(props: {
 			}
 
 			case 'emojiCode': {
-				// eslint-disable-next-line @typescript-eslint/no-unnecessary-condition
+				if (props.customEmojis && props.customEmojis[token.props.name]) {
+					return [h(MkCustomEmoji, {
+						key: Math.random(),
+						name: token.props.name,
+						normal: props.plain,
+						useOriginalSize: scale >= 2.5,
+						url: props.customEmojis[token.props.name],
+					})]
+				}
 				return [h(MkCustomEmoji, {
 					key: Math.random(),
 					name: token.props.name,
diff --git a/components/tools/avatar-decoration/MkNote.vue b/components/tools/mocks/MkNote.vue
similarity index 73%
rename from components/tools/avatar-decoration/MkNote.vue
rename to components/tools/mocks/MkNote.vue
index 572d458b..7389a050 100644
--- a/components/tools/avatar-decoration/MkNote.vue
+++ b/components/tools/mocks/MkNote.vue
@@ -1,5 +1,5 @@
 <template>
-    <div class="rounded-xl h-auto w-full px-4 py-3.5 md:px-8 md:py-7 flex max-w-sm border border-slate-300 dark:border-slate-950">
+    <div class="rounded-xl h-auto w-full px-4 py-3.5 md:px-8 md:py-7 flex max-w-md border border-slate-300 dark:border-slate-800">
         <div class="mr-3.5">
             <div class="w-[46px] h-[46px] md:w-[58px] md:h-[58px] relative rounded-full bg-slate-50 dark:bg-slate-900">
                 <img class="w-full h-full object-cover rounded-full" :src="avatar" />
@@ -16,7 +16,14 @@
                 <div class="font-bold">{{ $t('_avatarDecorationPreview._placeholder.username') }}</div>
                 <div class="opacity-70">@ai</div>
             </div>
-            <div>{{ $t('_avatarDecorationPreview._placeholder.noteText') }}</div>
+            <div><slot>{{ $t('_avatarDecorationPreview._placeholder.noteText') }}</slot></div>
+            <div class="mt-1 flex flex-wrap gap-2">
+                <span v-for="reaction in reactions" class="inline-flex items-center space-x-1 px-1.5 py-1 rounded bg-gray-100 dark:bg-gray-800">
+                    <MkCustomEmoji class="hover:!transform-none" v-if="reaction.name.startsWith(':')" :name="reaction.name" :url="reaction.url" :useOriginalSize="true" />
+                    <div v-else class="text-xl leading-[1.35] select-none">{{ reaction.name }}</div>
+                    <span class="text-sm">{{ reaction.count }}</span>
+                </span>
+            </div>
             <div class="flex space-x-3.5 md:space-x-7 opacity-60">
                 <div class="p-2"><ReplyIco class="w-3 h-3 md:h-4 md:w-4 block stroke-1 stroke-current reply" /></div>
                 <div class="p-2"><RenoteIco class="w-3 h-3 md:h-4 md:w-4 block stroke-1 stroke-current" /></div>
@@ -34,10 +41,17 @@ import RenoteIco from 'bi/repeat.svg';
 import ReactionIco from 'bi/plus-lg.svg';
 import MoreIco from 'bi/three-dots.svg';
 
-defineProps<{
-    avatar: string;
+withDefaults(defineProps<{
+    avatar?: string;
     decorations?: (Omit<Misskey.entities.User['avatarDecorations'][number], 'id'> & { offsetX?: number; offsetY?: number; })[];
-}>();
+    reactions?: {
+        name: string;
+        url?: string;
+        count: number;
+    }[];
+}>(), {
+    avatar: '/img/docs/fukidashi/doya_ai.webp',
+});
 
 function getStyle(decoration: Omit<Misskey.entities.User['avatarDecorations'][number], 'id'> & { offsetX?: number; offsetY?: number; }): HTMLAttributes['style'] {
     const angle = decoration.angle ?? 0;
diff --git a/components/tools/avatar-decoration/MkProf.vue b/components/tools/mocks/MkProf.vue
similarity index 92%
rename from components/tools/avatar-decoration/MkProf.vue
rename to components/tools/mocks/MkProf.vue
index 899e933c..2dfc1d4a 100644
--- a/components/tools/avatar-decoration/MkProf.vue
+++ b/components/tools/mocks/MkProf.vue
@@ -1,5 +1,5 @@
 <template>
-    <div class="rounded-xl h-auto w-72 border border-slate-300 dark:border-slate-950 bg-slate-200 dark:bg-slate-700">
+    <div class="rounded-xl h-auto w-72 border border-slate-300 dark:border-slate-800 bg-slate-200 dark:bg-slate-700">
         <div class="mt-[84px] bg-white dark:bg-slate-950 rounded-b-xl divide-y divide-slate-200 dark:divide-slate-900">
             <div class="flex items-center space-x-2 px-4 py-2">
                 <div class="w-[66px] h-[66px] relative -mt-8 rounded-full border-4 border-white dark:border-slate-950 bg-slate-50 dark:bg-slate-900">
@@ -24,10 +24,12 @@
 <script setup lang="ts">
 import type * as Misskey from 'misskey-js';
 
-defineProps<{
-    avatar: string;
+withDefaults(defineProps<{
+    avatar?: string;
     decorations?: (Omit<Misskey.entities.User['avatarDecorations'][number], 'id'> & { offsetX?: number; offsetY?: number; })[];
-}>();
+}>(), {
+    avatar: '/img/docs/fukidashi/doya_ai.webp',
+});
 
 function getStyle(decoration: Omit<Misskey.entities.User['avatarDecorations'][number], 'id'> & { offsetX?: number; offsetY?: number; }): HTMLAttributes['style'] {
     const angle = decoration.angle ?? 0;
diff --git a/locales/ja-JP.yml b/locales/ja-JP.yml
index a85dbd8e..c022fe13 100644
--- a/locales/ja-JP.yml
+++ b/locales/ja-JP.yml
@@ -7,6 +7,8 @@ share: "共有する"
 note: "ノート"
 other: "その他"
 add: "追加"
+browse: "参照"
+settings: "設定"
 goToLegacyHub: "従来のMisskey Hub"
 
 _error:
@@ -209,6 +211,8 @@ _tools:
   menuToggle: "メニュー"
   _forUsers:
     title: "Misskeyユーザー向け"
+  _forAdmin:
+    title: "サーバー運営者向け"
 
 _mfmPlayground:
   title: "MFMお試しコーナー"
@@ -317,6 +321,18 @@ _avatarDecorationPreview:
     noteText: "チョコのかかったドーナツを食べました🍩😋"
     profileDescription: "Misskey常駐AIの藍です！よろしくお願いします♪"
 
+_customEmojiPreview:
+  title: "カスタム絵文字 プレビュー"
+  description: "カスタム絵文字の視認性をチェックできます。"
+  preview: "プレビュー"
+  emoji: "絵文字 #{number}"
+  placeholder: "「追加」から、カスタム絵文字を追加してプレビューできます。"
+  _options:
+    text: "ノート文面"
+    textDescription: "追加したカスタム絵文字は{emoji_id}で参照できます。"
+  _placeholder:
+    noteText: "カスタム絵文字はこんな感じで表示されます→ :emoji_preview_0:\n文章を書き換えて、使い勝手を試してみてくださいね✨"
+
 _api:
   _permissions:
     title: "権限"
diff --git a/pages/tools/avatar-decoration-preview.vue b/pages/tools/avatar-decoration-preview.vue
index fd2345d9..d1989df5 100644
--- a/pages/tools/avatar-decoration-preview.vue
+++ b/pages/tools/avatar-decoration-preview.vue
@@ -10,11 +10,11 @@
                     {{ $t('_avatarDecorationPreview.preview') }}
                 </header>
                 <div class="flex gap-8 items-center justify-center flex-wrap">
-                    <ToolsAvatarDecorationMkProf
+                    <ToolsMocksMkProf
                         :avatar="avatar"
                         :decorations="realDecorations"
                     />
-                    <ToolsAvatarDecorationMkNote
+                    <ToolsMocksMkNote
                         :avatar="avatar"
                         :decorations="realDecorations"
                     />
diff --git a/pages/tools/custom-emoji-preview.vue b/pages/tools/custom-emoji-preview.vue
new file mode 100644
index 00000000..e6b09eb3
--- /dev/null
+++ b/pages/tools/custom-emoji-preview.vue
@@ -0,0 +1,162 @@
+<template>
+    <div class='container mx-auto max-w-screen-xl px-6 py-6'>
+        <h1 class='text-2xl lg:text-3xl font-bold mb-4'>
+            {{ $t('_customEmojiPreview.title') }}
+        </h1>
+
+        <div class="space-y-8">
+            <div class="p-6 space-y-4 rounded-lg bg-white dark:bg-slate-950">
+                <header class="-mt-6 -mx-6 px-6 py-3 font-bold text-lg border-b border-slate-300 dark:border-slate-800">
+                    {{ $t('_customEmojiPreview.preview') }}
+                </header>
+                <div class="flex gap-8 items-center justify-center flex-wrap">
+                    <ToolsMocksMkNote
+                        class="!max-w-xl"
+                        :reactions="[{
+                            name: '👍',
+                            count: 1,
+                        }, ...noteReactions]"
+                    >
+                        <MkMfm :text="text" :customEmojis="customEmojisDefinition" />
+                    </ToolsMocksMkNote>
+                </div>
+            </div>
+            <div class="grid md:grid-cols-5 gap-8">
+                <div class="p-6 space-y-4 rounded-lg bg-white dark:bg-slate-950 order-1 md:col-span-2 md:order-2">
+                    <header class="-mt-6 -mx-6 px-6 py-3 font-bold text-lg border-b border-slate-300 dark:border-slate-800">
+                        {{ $t('_customEmojiPreview._options.text') }}
+                    </header>
+                    <div>
+                        <label for="customEmojiPreviewText">{{ $t('_customEmojiPreview._options.text') }}</label>
+                        <textarea
+                            class="form-control"
+                            id="customEmojiPreviewText"
+                            rows="10"
+                            v-model="text"
+                        ></textarea>
+                    </div>
+                </div>
+                <div class="p-6 rounded-lg bg-white dark:bg-slate-950 order-2 md:col-span-3 md:order-1">
+                    <header class="-mt-6 -mx-6 px-6 py-3 border-b border-slate-300 dark:border-slate-800 flex items-center">
+                        <h2 class="font-bold text-lg">{{ $t('settings') }}</h2>
+                        <div class="ml-auto">
+                            <button class="btn btn-primary" @click="addEmoji()"><PlusIco class="mr-1" />{{ $t('add') }}</button>
+                        </div>
+                    </header>
+                    <div v-if="emojis.length === 0" class="p-8 text-center font-bold text-lg">
+                        {{ $t('_customEmojiPreview.placeholder') }}
+                    </div>
+                    <div v-for="emoji, index in emojis" :key="emoji.id" class="mt-8 p-4 rounded-lg bg-white dark:bg-slate-950 border border-slate-300 dark:border-slate-800">
+                        <h3 class="-mt-7 font-bold flex items-center w-fit px-3 bg-white dark:bg-slate-950 mb-4">
+                            <button type="button" class="btn btn-sm btn-outline-danger mr-2" @click="deleteEmoji(index)"><XIco class="h-3.5 w-3.5 stroke-1 stroke-current" /></button>
+                            <div>{{ $t('_customEmojiPreview.emoji', { number: emoji.id }) }}</div>
+                        </h3>
+                        <div class="lg:flex items-center space-y-4 lg:space-y-0 lg:space-x-4">
+                            <div class="mx-auto lg:mx-0 w-fit space-y-2 flex-shrink-0">
+                                <div
+                                    class="h-16 p-2 rounded-lg max-w-[200px] transition-colors"
+                                    :class="emoji.invertColorScheme ? 'bg-slate-800 dark:bg-slate-200' : 'bg-slate-200 dark:bg-slate-800'"
+                                >
+                                    <img class="h-full w-full object-contain" :src="getEmojiUrl(emoji)" />
+                                </div>
+                                <div class="w-min mx-auto form-check form-switch">
+                                    <input class="form-check-input" type="checkbox" role="switch" :id="`invertColorSchemeSwitch_${emoji.id}`" v-model="emojis[index].invertColorScheme">
+                                    <label v-if="colorMode.value === 'dark'" class="form-check-label" :for="`invertColorSchemeSwitch_${emoji.id}`"><SunIco /></label>
+                                    <label v-else class="form-check-label" :for="`invertColorSchemeSwitch_${emoji.id}`"><MoonIco /></label>
+                                </div>
+                            </div>
+                            <I18nT scope="global" keypath="_customEmojiPreview._options.textDescription" tag="div">
+                                <template #emoji_id>
+                                    <code class="inline-block text-sm bg-slate-200 dark:bg-slate-800 mx-0.5 p-0.5 rounded">{{ noteReactions[index].name }}</code>
+                                </template>
+                            </I18nT>
+                        </div>
+                    </div>
+                </div>
+            </div>
+        </div>
+    </div>
+</template>
+
+<script setup lang='ts'>
+import PlusIco from 'bi/plus-lg.svg';
+import XIco from 'bi/x-lg.svg';
+import SunIco from 'bi/sun.svg';
+import MoonIco from 'bi/moon.svg';
+import { on } from 'events';
+
+definePageMeta({
+    layout: 'tools',
+});
+
+const { t } = useI18n();
+const route = useRoute();
+const colorMode = useColorMode();
+
+const text = ref(t('_customEmojiPreview._placeholder.noteText'));
+
+const emojis = ref<{
+    id: number;
+    file: string | Blob;
+    invertColorScheme: boolean;
+}[]>([{
+    id: 0,
+    file: '/img/emojis/rocket_3d.png',
+    invertColorScheme: false,
+}]);
+
+const noteReactions = computed(() => emojis.value?.map((emoji) => ({
+    name: `:emoji_preview_${emoji.id}:`,
+    code: `emoji_preview_${emoji.id}`,
+    url: (typeof emoji.file !== 'string') ? URL.createObjectURL(emoji.file) : emoji.file,
+    count: 1,
+})) ?? []);
+
+const customEmojisDefinition = computed(() => Object.fromEntries(noteReactions.value?.map((emoji) => [ emoji.code, emoji.url ]) ?? []));
+
+function deleteEmoji(index: number) {
+    emojis.value.splice(index, 1);
+}
+
+function getEmojiUrl(emoji: { id: number; file: string | Blob; }) {
+    return (typeof emoji.file !== 'string') ? URL.createObjectURL(emoji.file) : emoji.file;
+}
+
+function addEmoji() {
+    if (!process.client) return;
+
+    const input = document.createElement('input');
+    input.type = 'file';
+    input.accept = 'image/*';
+    input.addEventListener('change', (event) => {
+        const file = (event.target as HTMLInputElement).files?.[0];
+        if (!file) return;
+
+        emojis.value.push({
+            id: emojis.value.length,
+            file,
+            invertColorScheme: false,
+        });
+
+        input.remove();
+    });
+
+    input.click();
+}
+
+onBeforeUnmount(() => {
+    for (const emoji of noteReactions.value) {
+        if (emoji.url.startsWith('blob:')) {
+            URL.revokeObjectURL(emoji.url);
+        }
+    }
+    emojis.value = [];
+});
+
+route.meta.title = t('_customEmojiPreview.title');
+route.meta.description = t('_customEmojiPreview.description');
+</script>
+
+<style module>
+
+</style>