diff --git a/locales/ja-JP.yml b/locales/ja-JP.yml
index f85e8f3e00..62aade568d 100644
--- a/locales/ja-JP.yml
+++ b/locales/ja-JP.yml
@@ -614,7 +614,6 @@ regenerateLoginToken: "ログイントークンを再生成"
 regenerateLoginTokenDescription: "ログインに使用される内部トークンを再生成します。通常この操作を行う必要はありません。再生成すると、全てのデバイスでログアウトされます。"
 setMultipleBySeparatingWithSpace: "スペースで区切って複数設定できます。"
 fileIdOrUrl: "ファイルIDまたはURL"
-chatOpenBehavior: "チャットを開くときの動作"
 behavior: "動作"
 sample: "サンプル"
 abuseReports: "通報"
diff --git a/packages/client/src/components/global/a.vue b/packages/client/src/components/global/a.vue
index 5db61203c6..77ee7525a4 100644
--- a/packages/client/src/components/global/a.vue
+++ b/packages/client/src/components/global/a.vue
@@ -106,11 +106,6 @@ export default defineComponent({
 				return;
 			}
 
-			if (this.to.startsWith('/my/messaging')) {
-				if (ColdDeviceStorage.get('chatOpenBehavior') === 'window') return this.window();
-				if (ColdDeviceStorage.get('chatOpenBehavior') === 'popout') return this.popout();
-			}
-
 			if (this.behavior) {
 				if (this.behavior === 'window') {
 					return this.window();
diff --git a/packages/client/src/pages/settings/general.vue b/packages/client/src/pages/settings/general.vue
index 83924382d8..734bc78442 100644
--- a/packages/client/src/pages/settings/general.vue
+++ b/packages/client/src/pages/settings/general.vue
@@ -77,13 +77,6 @@
 		<FormSwitch v-model="defaultSideView">{{ $ts.openInSideView }}</FormSwitch>
 	</FormGroup>
 
-	<FormSelect v-model="chatOpenBehavior" class="_formBlock">
-		<template #label>{{ $ts.chatOpenBehavior }}</template>
-		<option value="page">{{ $ts.showInPage }}</option>
-		<option value="window">{{ $ts.openInWindow }}</option>
-		<option value="popout">{{ $ts.popout }}</option>
-	</FormSelect>
-
 	<FormLink to="/settings/deck" class="_formBlock">{{ $ts.deck }}</FormLink>
 
 	<FormLink to="/settings/custom-css" class="_formBlock"><template #icon><i class="fas fa-code"></i></template>{{ $ts.customCss }}</FormLink>
@@ -149,7 +142,6 @@ export default defineComponent({
 		disablePagesScript: defaultStore.makeGetterSetter('disablePagesScript'),
 		showFixedPostForm: defaultStore.makeGetterSetter('showFixedPostForm'),
 		defaultSideView: defaultStore.makeGetterSetter('defaultSideView'),
-		chatOpenBehavior: ColdDeviceStorage.makeGetterSetter('chatOpenBehavior'),
 		instanceTicker: defaultStore.makeGetterSetter('instanceTicker'),
 		enableInfiniteScroll: defaultStore.makeGetterSetter('enableInfiniteScroll'),
 		useReactionPickerForContextMenu: defaultStore.makeGetterSetter('useReactionPickerForContextMenu'),
diff --git a/packages/client/src/store.ts b/packages/client/src/store.ts
index 19d46bacea..dc9c3b7b9e 100644
--- a/packages/client/src/store.ts
+++ b/packages/client/src/store.ts
@@ -245,7 +245,6 @@ export class ColdDeviceStorage {
 		lightTheme: require('@/themes/l-light.json5') as Theme,
 		darkTheme: require('@/themes/d-dark.json5') as Theme,
 		syncDeviceDarkMode: true,
-		chatOpenBehavior: 'page' as 'page' | 'window' | 'popout',
 		plugins: [] as Plugin[],
 		mediaVolume: 0.5,
 		sound_masterVolume: 0.3,