diff --git a/CALCKEY.md b/CALCKEY.md
index f977f35aba..1e4a233164 100644
--- a/CALCKEY.md
+++ b/CALCKEY.md
@@ -20,6 +20,7 @@
 
 ## Work in progress
 
+- OCR image/video captioning
 - Recommended instances timeline
 - Admin custom CSS
 - Improve accesibility score
diff --git a/locales/en-US.yml b/locales/en-US.yml
index c5c43bf1a6..d7e8c224b7 100644
--- a/locales/en-US.yml
+++ b/locales/en-US.yml
@@ -911,6 +911,7 @@ customSplashIconsDescription: "URLs for custom splash screen icons separated by
 showUpdates: "Show a popup when Calckey updates"
 recommendedInstances: "Recommended instances"
 recommendedInstancesDescription: "Recommended instances seperated by line breaks to appear in the recommended timeline. Do NOT add `https://`, ONLY the domain."
+caption: "Auto Caption"
 
 _sensitiveMediaDetection:
   description: "Reduces the effort of server moderation through automatically recognizing NSFW media via Machine Learning. This will slightly increase the load on the server."
diff --git a/locales/ja-JP.yml b/locales/ja-JP.yml
index c80ca8e9b7..ac7154de2a 100644
--- a/locales/ja-JP.yml
+++ b/locales/ja-JP.yml
@@ -911,6 +911,7 @@ customSplashIconsDescription: "ユーザがページをロード/リロードす
 showUpdates: "Calckeyの更新時にポップアップを表示する"
 recommendedInstances: "推奨インスタンス"
 recommendedInstancesDescription: "推奨タイムラインに表示するために改行で区切られた推奨インスタンス。`https：//`を追加しないでください。ドメインのみを追加してください。"
+caption: "自動キャプション"
 
 _sensitiveMediaDetection:
   description: "機械学習を使って自動でセンシティブなメディアを検出し、モデレーションに役立てることができます。サーバーの負荷が少し増えます。"
diff --git a/package.json b/package.json
index 5fda2f7c8b..fa3d8dc808 100644
--- a/package.json
+++ b/package.json
@@ -1,6 +1,6 @@
 {
 	"name": "misskey",
-	"version": "12.118.1-calc.rc.3",
+	"version": "12.118.1-calc.rc.4",
 	"codename": "aqua",
 	"repository": {
 		"type": "git",
diff --git a/packages/client/package.json b/packages/client/package.json
index 664d0f7d50..d76eafd5d5 100644
--- a/packages/client/package.json
+++ b/packages/client/package.json
@@ -47,6 +47,7 @@
 		"strict-event-emitter-types": "2.0.0",
 		"stringz": "2.1.0",
 		"syuilo-password-strength": "0.0.1",
+		"tesseract.js": "^2.1.5",
 		"textarea-caret": "3.1.0",
 		"three": "0.143.0",
 		"throttle-debounce": "5.0.0",
diff --git a/packages/client/src/components/gallery-post-preview.vue b/packages/client/src/components/gallery-post-preview.vue
index 8245902976..082ac669d7 100644
--- a/packages/client/src/components/gallery-post-preview.vue
+++ b/packages/client/src/components/gallery-post-preview.vue
@@ -31,7 +31,7 @@ export default defineComponent({
 		},
 	},
 	methods: {
-		userName
+		userName,
 	}
 });
 </script>
diff --git a/packages/client/src/components/media-caption.vue b/packages/client/src/components/media-caption.vue
index feed3854f9..b6285902d6 100644
--- a/packages/client/src/components/media-caption.vue
+++ b/packages/client/src/components/media-caption.vue
@@ -1,40 +1,46 @@
 <template>
-	<MkModal ref="modal" @click="done(true)" @closed="$emit('closed')">
-		<div class="container">
-			<div class="fullwidth top-caption">
-				<div class="mk-dialog">
-					<header>
-						<Mfm v-if="title" class="title" :text="title"/>
-						<span class="text-count" :class="{ over: remainingLength < 0 }">{{ remainingLength }}</span>
-					</header>
-					<textarea v-model="inputValue" autofocus :placeholder="input.placeholder" @keydown="onInputKeydown"></textarea>
-					<div v-if="(showOkButton || showCancelButton)" class="buttons">
-						<MkButton inline primary :disabled="remainingLength < 0" @click="ok">{{ $ts.ok }}</MkButton>
-						<MkButton inline @click="cancel" >{{ $ts.cancel }}</MkButton>
-					</div>
+<MkModal ref="modal" @click="done(true)" @closed="$emit('closed')">
+	<div class="container">
+		<div class="fullwidth top-caption">
+			<div class="mk-dialog">
+				<header>
+					<Mfm v-if="title" class="title" :text="title"/>
+					<span class="text-count" :class="{ over: remainingLength < 0 }">{{ remainingLength }}</span>
+				</header>
+				<textarea v-model="inputValue" autofocus :placeholder="input.placeholder" @keydown="onInputKeydown"></textarea>
+				<div v-if="(showOkButton || showCaptionButton || showCancelButton)" class="buttons">
+					<MkButton inline primary :disabled="remainingLength < 0" @click="ok">{{ $ts.ok }}</MkButton>
+					<MkButton inline @click="caption" >{{ $ts.caption }}</MkButton>
+					<MkButton inline @click="cancel" >{{ $ts.cancel }}</MkButton>
 				</div>
 			</div>
-			<div class="hdrwpsaf fullwidth">
-				<header>{{ image.name }}</header>
-				<img :src="image.url" :alt="image.comment" :title="image.comment" @click="$refs.modal.close()"/>
-				<footer>
-					<span>{{ image.type }}</span>
-					<span>{{ bytes(image.size) }}</span>
-					<span v-if="image.properties && image.properties.width">{{ number(image.properties.width) }}px × {{ number(image.properties.height) }}px</span>
-				</footer>
-			</div>
 		</div>
-	</MkModal>
+		<div class="hdrwpsaf fullwidth">
+			<header>{{ image.name }}</header>
+			<img id="imgtocaption" :src="image.url" :alt="image.comment" :title="image.comment" @click="$refs.modal.close()"/>
+			<footer>
+				<span>{{ image.type }}</span>
+				<span>{{ bytes(image.size) }}</span>
+				<span v-if="image.properties && image.properties.width">{{ number(image.properties.width) }}px × {{ number(image.properties.height) }}px</span>
+			</footer>
+		</div>
+	</div>
+</MkModal>
 </template>
 
 <script lang="ts">
 import { defineComponent } from 'vue';
 import { length } from 'stringz';
+import { createWorker, PSM, OEM } from 'tesseract.js';
 import MkModal from '@/components/ui/modal.vue';
 import MkButton from '@/components/ui/button.vue';
 import bytes from '@/filters/bytes';
 import number from '@/filters/number';
 
+const worker = createWorker({
+	logger: m => console.log(m),
+});
+
 export default defineComponent({
 	components: {
 		MkModal,
@@ -48,22 +54,26 @@ export default defineComponent({
 		},
 		title: {
 			type: String,
-			required: false
+			required: false,
 		},
 		input: {
-			required: true
+			required: true,
 		},
 		showOkButton: {
 			type: Boolean,
-			default: true
+			default: true,
+		},
+		showCaptionButton: {
+			type: Boolean,
+			default: true,
 		},
 		showCancelButton: {
 			type: Boolean,
-			default: true
+			default: true,
 		},
 		cancelableByBgClick: {
 			type: Boolean,
-			default: true
+			default: true,
 		},
 	},
 
@@ -93,6 +103,8 @@ export default defineComponent({
 	methods: {
 		bytes,
 		number,
+		PSM,
+		OEM,
 
 		done(canceled, result?) {
 			this.$emit('done', { canceled, result });
@@ -130,8 +142,20 @@ export default defineComponent({
 					this.ok();
 				}
 			}
-		}
-	}
+		},
+
+		caption: async () => {
+			const img = document.getElementById('imgtocaption');
+			await worker.load();
+			await worker.loadLanguage('eng');
+			await worker.initialize('eng', OEM.LSTM_ONLY);
+			await worker.setParameters({
+				tessedit_pageseg_mode: PSM.SINGLE_BLOCK,
+			});
+			const { data: { text } } = await worker.recognize(img);
+			console.log(text);
+		},
+	},
 });
 </script>
 
diff --git a/yarn.lock b/yarn.lock
index bc60047b5b..c239f1bee4 100644
--- a/yarn.lock
+++ b/yarn.lock
@@ -3210,6 +3210,13 @@ __metadata:
   languageName: node
   linkType: hard
 
+"blueimp-load-image@npm:^3.0.0":
+  version: 3.0.0
+  resolution: "blueimp-load-image@npm:3.0.0"
+  checksum: 19a1e9a76ea87e15c1624c3ed30536f094252f0a65a193239f54ec0c25fe480b5140c962ac41a66f35a2d19b58d9da26803287b5a37b78d82d4b23328b09bf4a
+  languageName: node
+  linkType: hard
+
 "blurhash@npm:1.1.5":
   version: 1.1.5
   resolution: "blurhash@npm:1.1.5"
@@ -3217,6 +3224,13 @@ __metadata:
   languageName: node
   linkType: hard
 
+"bmp-js@npm:^0.1.0":
+  version: 0.1.0
+  resolution: "bmp-js@npm:0.1.0"
+  checksum: 2f6cf7eeabae2aa50eb768122f59e9752caa97248028cb8b5cf0d9db7cf8fb3a60262aeb2c6889dd21357ab061b2fb318f21f20d2b24963ba36ead8e264c6654
+  languageName: node
+  linkType: hard
+
 "bn.js@npm:^4.0.0":
   version: 4.12.0
   resolution: "bn.js@npm:4.12.0"
@@ -3950,6 +3964,7 @@ __metadata:
     strict-event-emitter-types: 2.0.0
     stringz: 2.1.0
     syuilo-password-strength: 0.0.1
+    tesseract.js: ^2.1.5
     textarea-caret: 3.1.0
     three: 0.143.0
     throttle-debounce: 5.0.0
@@ -4229,6 +4244,13 @@ __metadata:
   languageName: node
   linkType: hard
 
+"colors@npm:^1.4.0":
+  version: 1.4.0
+  resolution: "colors@npm:1.4.0"
+  checksum: 98aa2c2418ad87dedf25d781be69dc5fc5908e279d9d30c34d8b702e586a0474605b3a189511482b9d5ed0d20c867515d22749537f7bc546256c6014f3ebdcec
+  languageName: node
+  linkType: hard
+
 "colors@npm:~1.1.2":
   version: 1.1.2
   resolution: "colors@npm:1.1.2"
@@ -6385,6 +6407,13 @@ __metadata:
   languageName: node
   linkType: hard
 
+"file-type@npm:^12.4.1":
+  version: 12.4.2
+  resolution: "file-type@npm:12.4.2"
+  checksum: 67c8d7f8f032fd8cf4d14016d96567d20eeb7bf3524915f2c5d79337ca4e5338032d373a5fe827610eaf4ab7eb80629ff868331a66f63d1f9e9cc4c433e3f047
+  languageName: node
+  linkType: hard
+
 "filelist@npm:^1.0.1":
   version: 1.0.4
   resolution: "filelist@npm:1.0.4"
@@ -7036,7 +7065,7 @@ __metadata:
   languageName: node
   linkType: hard
 
-"glob@npm:^7.1.1, glob@npm:^7.1.3, glob@npm:^7.1.4, glob@npm:^7.2.0":
+"glob@npm:^7.1.1, glob@npm:^7.1.3, glob@npm:^7.1.4, glob@npm:^7.1.6, glob@npm:^7.2.0":
   version: 7.2.3
   resolution: "glob@npm:7.2.3"
   dependencies:
@@ -7708,6 +7737,13 @@ __metadata:
   languageName: node
   linkType: hard
 
+"idb-keyval@npm:^3.2.0":
+  version: 3.2.0
+  resolution: "idb-keyval@npm:3.2.0"
+  checksum: 3270010af049fa7f07b0381818daa7f16d3704aaba9d2585e531908f09130f6d0772464b2b48c23676dd1e51e5245585da5ce56f2c74dfd4f9961d1e0d0f5909
+  languageName: node
+  linkType: hard
+
 "ieee754@npm:1.1.13":
   version: 1.1.13
   resolution: "ieee754@npm:1.1.13"
@@ -8098,6 +8134,13 @@ __metadata:
   languageName: node
   linkType: hard
 
+"is-electron@npm:^2.2.0":
+  version: 2.2.1
+  resolution: "is-electron@npm:2.2.1"
+  checksum: 06e569aa933a737d418489bb9ca081af62eceb714d4c3d553ad2497610e35494be6dddd010c4e29890c7dd9d0481c2e3e1e9097af9d19df1c52dd5be747d80a0
+  languageName: node
+  linkType: hard
+
 "is-expression@npm:^4.0.0":
   version: 4.0.0
   resolution: "is-expression@npm:4.0.0"
@@ -8411,6 +8454,13 @@ __metadata:
   languageName: node
   linkType: hard
 
+"is-url@npm:^1.2.4":
+  version: 1.2.4
+  resolution: "is-url@npm:1.2.4"
+  checksum: 100e74b3b1feab87a43ef7653736e88d997eb7bd32e71fd3ebc413e58c1cbe56269699c776aaea84244b0567f2a7d68dfaa512a062293ed2f9fdecb394148432
+  languageName: node
+  linkType: hard
+
 "is-utf8@npm:^0.2.0, is-utf8@npm:^0.2.1":
   version: 0.2.1
   resolution: "is-utf8@npm:0.2.1"
@@ -8536,6 +8586,21 @@ __metadata:
   languageName: node
   linkType: hard
 
+"jpeg-autorotate@npm:^7.1.1":
+  version: 7.1.1
+  resolution: "jpeg-autorotate@npm:7.1.1"
+  dependencies:
+    colors: ^1.4.0
+    glob: ^7.1.6
+    jpeg-js: ^0.4.2
+    piexifjs: ^1.0.6
+    yargs-parser: ^20.2.1
+  bin:
+    jpeg-autorotate: src/cli.js
+  checksum: fdd6898ed287e074e26667e503731846ddb3e3042d5aee70f3f6ae86051b8d493bfa0906f9df19a4e5fb0df6253ff059bf8967cda5fb3e6f1c8e8e2d7a58a3ee
+  languageName: node
+  linkType: hard
+
 "jpeg-js@npm:^0.3.2":
   version: 0.3.7
   resolution: "jpeg-js@npm:0.3.7"
@@ -8543,7 +8608,7 @@ __metadata:
   languageName: node
   linkType: hard
 
-"jpeg-js@npm:^0.4.1":
+"jpeg-js@npm:^0.4.1, jpeg-js@npm:^0.4.2":
   version: 0.4.4
   resolution: "jpeg-js@npm:0.4.4"
   checksum: bd7cb61aa8df40a9ee2c2106839c3df6054891e56cfc22c0ac581402e06c6295f962a4754b0b2ac50a401789131b1c6dc9df8d24400f1352168be1894833c590
@@ -10316,7 +10381,7 @@ __metadata:
   languageName: node
   linkType: hard
 
-"node-fetch@npm:^2.6.1, node-fetch@npm:^2.6.7, node-fetch@npm:~2.6.1":
+"node-fetch@npm:^2.6.0, node-fetch@npm:^2.6.1, node-fetch@npm:^2.6.7, node-fetch@npm:~2.6.1":
   version: 2.6.7
   resolution: "node-fetch@npm:2.6.7"
   dependencies:
@@ -10728,6 +10793,15 @@ __metadata:
   languageName: node
   linkType: hard
 
+"opencollective-postinstall@npm:^2.0.2":
+  version: 2.0.3
+  resolution: "opencollective-postinstall@npm:2.0.3"
+  bin:
+    opencollective-postinstall: index.js
+  checksum: 0a68c5cef135e46d11e665d5077398285d1ce5311c948e8327b435791c409744d4a6bb9c55bd6507fb5f2ef34b0ad920565adcdaf974cbdae701aead6f32b396
+  languageName: node
+  linkType: hard
+
 "opentype.js@npm:^0.4.3":
   version: 0.4.11
   resolution: "opentype.js@npm:0.4.11"
@@ -11262,6 +11336,13 @@ __metadata:
   languageName: node
   linkType: hard
 
+"piexifjs@npm:^1.0.6":
+  version: 1.0.6
+  resolution: "piexifjs@npm:1.0.6"
+  checksum: 137caf5ca36c0ad98cfd445c0ec40737f7589469e750ac417a2019b940cf6534e9834f3f01dc6a85a6d6c127c3eb5b5dc750812c800e6567392b67da94a755bd
+  languageName: node
+  linkType: hard
+
 "pify@npm:^2.0.0, pify@npm:^2.2.0":
   version: 2.3.0
   resolution: "pify@npm:2.3.0"
@@ -12412,7 +12493,7 @@ __metadata:
   languageName: node
   linkType: hard
 
-"regenerator-runtime@npm:^0.13.4, regenerator-runtime@npm:^0.13.5":
+"regenerator-runtime@npm:^0.13.3, regenerator-runtime@npm:^0.13.4, regenerator-runtime@npm:^0.13.5":
   version: 0.13.9
   resolution: "regenerator-runtime@npm:0.13.9"
   checksum: 65ed455fe5afd799e2897baf691ca21c2772e1a969d19bb0c4695757c2d96249eb74ee3553ea34a91062b2a676beedf630b4c1551cc6299afb937be1426ec55e
@@ -13895,6 +13976,34 @@ __metadata:
   languageName: node
   linkType: hard
 
+"tesseract.js-core@npm:^2.2.0":
+  version: 2.2.0
+  resolution: "tesseract.js-core@npm:2.2.0"
+  checksum: 7587514a6bd51540ba7bbe1fd6349a83c5865261db43bee1625b07c877ac6949b1bf7e0a9a84b6925f8acfb34287f9c28dfd3f3d1bbaa49abc9cbb6cb7927389
+  languageName: node
+  linkType: hard
+
+"tesseract.js@npm:^2.1.5":
+  version: 2.1.5
+  resolution: "tesseract.js@npm:2.1.5"
+  dependencies:
+    blueimp-load-image: ^3.0.0
+    bmp-js: ^0.1.0
+    file-type: ^12.4.1
+    idb-keyval: ^3.2.0
+    is-electron: ^2.2.0
+    is-url: ^1.2.4
+    jpeg-autorotate: ^7.1.1
+    node-fetch: ^2.6.0
+    opencollective-postinstall: ^2.0.2
+    regenerator-runtime: ^0.13.3
+    resolve-url: ^0.2.1
+    tesseract.js-core: ^2.2.0
+    zlibjs: ^0.3.1
+  checksum: a28a2edae162ab5db97a9337dbce1ea96f3c303f6976560784d9f774be6fec15b05f04b8776fe6b9d12471324ee0c94fe25efd2d991fdb859ad66d24e8d66fb0
+  languageName: node
+  linkType: hard
+
 "text-table@npm:^0.2.0":
   version: 0.2.0
   resolution: "text-table@npm:0.2.0"
@@ -15433,7 +15542,7 @@ __metadata:
   languageName: node
   linkType: hard
 
-"yargs-parser@npm:^20.2.2":
+"yargs-parser@npm:^20.2.1, yargs-parser@npm:^20.2.2":
   version: 20.2.9
   resolution: "yargs-parser@npm:20.2.9"
   checksum: 8bb69015f2b0ff9e17b2c8e6bfe224ab463dd00ca211eece72a4cd8a906224d2703fb8a326d36fdd0e68701e201b2a60ed7cf81ce0fd9b3799f9fe7745977ae3
@@ -15573,3 +15682,10 @@ __metadata:
   checksum: 4a73da856738b0634700b52f4ab3fe0bf0a532bea6820ad962d0bda0163d2d5525df4859f89a7238e204a378384e12551985049790c1894c3ac191866e85887f
   languageName: node
   linkType: hard
+
+"zlibjs@npm:^0.3.1":
+  version: 0.3.1
+  resolution: "zlibjs@npm:0.3.1"
+  checksum: 91f3d28bb5925ac71565a1fd4d44303b6b876ed483c9c192864393811151b399f29d917c9118a5aca5a541d9dfc7c199460f86b489ea1f77b7217e0edc887c89
+  languageName: node
+  linkType: hard