diff --git a/configs/i18n-completeness.ts b/configs/i18n-completeness.ts
new file mode 100644
index 000000000..3de328b31
--- /dev/null
+++ b/configs/i18n-completeness.ts
@@ -0,0 +1,60 @@
+import fs from "node:fs"
+import path from "node:path"
+
+type LanguageCompletion = Record<string, number>
+
+function getLanguageFiles(dir: string): string[] {
+  return fs.readdirSync(dir).filter((file) => file.endsWith(".json"))
+}
+
+function getNamespaces(localesDir: string): string[] {
+  return fs
+    .readdirSync(localesDir)
+    .filter((file) => fs.statSync(path.join(localesDir, file)).isDirectory())
+}
+
+function countKeys(obj: any): number {
+  let count = 0
+  for (const key in obj) {
+    if (typeof obj[key] === "object") {
+      count += countKeys(obj[key])
+    } else {
+      count++
+    }
+  }
+  return count
+}
+
+function calculateCompleteness(localesDir: string): LanguageCompletion {
+  const namespaces = getNamespaces(localesDir)
+  const languages = new Set<string>()
+  const keyCount: Record<string, number> = {}
+
+  namespaces.forEach((namespace) => {
+    const namespaceDir = path.join(localesDir, namespace)
+    const files = getLanguageFiles(namespaceDir)
+
+    files.forEach((file) => {
+      const lang = path.basename(file, ".json")
+      languages.add(lang)
+
+      const content = JSON.parse(fs.readFileSync(path.join(namespaceDir, file), "utf-8"))
+      keyCount[lang] = (keyCount[lang] || 0) + countKeys(content)
+    })
+  })
+
+  const enCount = keyCount["en"] || 0
+  const completeness: LanguageCompletion = {}
+
+  languages.forEach((lang) => {
+    if (lang !== "en") {
+      const percent = Math.round((keyCount[lang] / enCount) * 100)
+      completeness[lang] = percent
+    }
+  })
+
+  return completeness
+}
+
+const i18n = calculateCompleteness(path.resolve(__dirname, "../locales"))
+export default i18n
diff --git a/configs/vite.render.config.ts b/configs/vite.render.config.ts
index 36dd7d4f3..8dfb9747b 100644
--- a/configs/vite.render.config.ts
+++ b/configs/vite.render.config.ts
@@ -11,6 +11,7 @@ import { prerelease } from "semver"
 import type { Plugin, UserConfig } from "vite"
 
 import { getGitHash } from "../scripts/lib"
+import i18nCompleteness from "./i18n-completeness"
 
 const pkg = JSON.parse(readFileSync("package.json", "utf8"))
 const isCI = process.env.CI === "true" || process.env.CI === "1"
@@ -134,6 +135,8 @@ export const viteRenderBaseConfig = {
     RELEASE_CHANNEL: JSON.stringify((prerelease(pkg.version)?.[0] as string) || "stable"),
 
     DEBUG: process.env.DEBUG === "true",
+
+    I18N_COMPLETENESS_MAP: JSON.stringify({ ...i18nCompleteness, en: 100 }),
   },
 } satisfies UserConfig
 
diff --git a/locales/app/en.json b/locales/app/en.json
index 18249e9ef..fe3cc71a9 100644
--- a/locales/app/en.json
+++ b/locales/app/en.json
@@ -2,6 +2,9 @@
   "ai_daily.title": "Top News - {{title}}",
   "ai_daily.tooltip.content": "Here is news selected by AI from your timeline (<From /> - <To />) that may be important to you.",
   "ai_daily.tooltip.update_schedule": "Update daily at 8 AM and 8 PM.",
+  "app.app_name": "APP_NAME",
+  "app.copy_logo_svg": "Copy Logo SVG",
+  "app.toggle_sidebar": "Toggle Sidebar",
   "discover.any_url_or_keyword": "Any URL or Keyword",
   "discover.default_option": " (default)",
   "discover.feed_description": "The description of this feed is as follows, and you can fill out the parameter form with the relevant information.",
diff --git a/locales/app/zh-CN.json b/locales/app/zh-CN.json
index 8e9f43af6..60bbaab6e 100644
--- a/locales/app/zh-CN.json
+++ b/locales/app/zh-CN.json
@@ -2,6 +2,9 @@
   "ai_daily.title": "头条 - {{title}}",
   "ai_daily.tooltip.content": "这里是通过 AI 从您的时间线中选择的头条新闻（<From /> - <To />），可能对您很重要。",
   "ai_daily.tooltip.update_schedule": "每天早上 8 点、晚上 8 点更新。",
+  "app.app_name": "APP_NAME",
+  "app.copy_logo_svg": "复制 Logo SVG",
+  "app.toggle_sidebar": "切换侧边栏",
   "discover.any_url_or_keyword": "任何 URL 或关键词",
   "discover.default_option": " (默认)",
   "discover.feed_description": "此 Feed 的描述如下，您可以填写相关信息。",
diff --git a/locales/common/en.json b/locales/common/en.json
index 5350e008e..70164b71b 100644
--- a/locales/common/en.json
+++ b/locales/common/en.json
@@ -1,4 +1,5 @@
 {
+  "app.copied_to_clipboard": "Copied to clipboard",
   "cancel": "Cancel",
   "confirm": "Confirm",
   "ok": "OK",
diff --git a/locales/common/ja.json b/locales/common/ja.json
new file mode 100644
index 000000000..14fb7935e
--- /dev/null
+++ b/locales/common/ja.json
@@ -0,0 +1,28 @@
+{
+  "app.copied_to_clipboard": "クリップボードにコピーしました",
+  "cancel": "キャンセル",
+  "confirm": "確認",
+  "ok": "OK",
+  "quantifier.piece": "個",
+  "time.last_night": "昨夜",
+  "time.the_night_before_last": "一昨夜",
+  "time.today": "今日",
+  "time.yesterday": "昨日",
+  "tips.load-lng-error": "言語パックの読み込みに失敗しました",
+  "words.back": "戻る",
+  "words.copy": "コピー",
+  "words.edit": "編集",
+  "words.entry": "エントリー",
+  "words.id": "ID",
+  "words.items_one": "アイテム",
+  "words.items_other": "アイテム",
+  "words.local": "ローカル",
+  "words.record": "記録",
+  "words.record_one": "記録",
+  "words.record_other": "記録",
+  "words.result": "結果",
+  "words.result_one": "結果",
+  "words.result_other": "結果",
+  "words.space": "",
+  "words.which.all": "すべて"
+}
diff --git a/locales/common/zh-CN.json b/locales/common/zh-CN.json
index 9d94f3309..d68419a69 100644
--- a/locales/common/zh-CN.json
+++ b/locales/common/zh-CN.json
@@ -1,4 +1,5 @@
 {
+  "app.copied_to_clipboard": "已复制到剪贴板",
   "cancel": "取消",
   "confirm": "确认",
   "ok": "好",
diff --git a/locales/lang/en.json b/locales/lang/en.json
index e6f2d29f5..795047911 100644
--- a/locales/lang/en.json
+++ b/locales/lang/en.json
@@ -1,5 +1,6 @@
 {
   "langs.en": "English",
-  "langs.zh-CN": "简体中文（部分完成）",
+  "langs.ja": "日本語",
+  "langs.zh-CN": "简体中文",
   "name": "English"
 }
diff --git a/locales/lang/ja.json b/locales/lang/ja.json
new file mode 100644
index 000000000..cdd1c6e6c
--- /dev/null
+++ b/locales/lang/ja.json
@@ -0,0 +1,6 @@
+{
+  "langs.en": "English",
+  "langs.ja": "日本語",
+  "langs.zh-CN": "简体中文",
+  "name": "日本語"
+}
diff --git a/locales/lang/zh-CN.json b/locales/lang/zh-CN.json
index e6f2d29f5..48ce191a7 100644
--- a/locales/lang/zh-CN.json
+++ b/locales/lang/zh-CN.json
@@ -1,5 +1,6 @@
 {
   "langs.en": "English",
-  "langs.zh-CN": "简体中文（部分完成）",
-  "name": "English"
+  "langs.ja": "日本語",
+  "langs.zh-CN": "简体中文",
+  "name": "简体中文"
 }
diff --git a/src/renderer/src/@types/constants.ts b/src/renderer/src/@types/constants.ts
index f6bac9017..94c2bebd3 100644
--- a/src/renderer/src/@types/constants.ts
+++ b/src/renderer/src/@types/constants.ts
@@ -1,16 +1,9 @@
-export const currentSupportedLanguages = (() => {
-  const langsFiles = import.meta.glob("../../../../locales/app/*.json")
-
-  const langs = [] as string[]
-  for (const key in langsFiles) {
-    langs.push(key.split("/").pop()?.replace(".json", "") as string)
-  }
-  return langs
-})()
+export const currentSupportedLanguages = ["en", "ja", "zh-CN"]
 
 export const dayjsLocaleImportMap = {
   en: ["en", () => import("dayjs/locale/en")],
   ["zh-CN"]: ["zh-cn", () => import("dayjs/locale/zh-cn")],
+  ["ja"]: ["ja", () => import("dayjs/locale/ja")],
 }
 
 export const ns = ["app", "common", "lang", "settings", "shortcuts"] as const
diff --git a/src/renderer/src/@types/default-resource.ts b/src/renderer/src/@types/default-resource.ts
index 51ddc8165..28c271ac8 100644
--- a/src/renderer/src/@types/default-resource.ts
+++ b/src/renderer/src/@types/default-resource.ts
@@ -1,8 +1,10 @@
 import en from "../../../../locales/app/en.json"
 import common_en from "../../../../locales/common/en.json"
+import common_ja from "../../../../locales/common/ja.json"
 import common_zhCN from "../../../../locales/common/zh-CN.json"
 import external_en from "../../../../locales/external/en.json"
 import lang_en from "../../../../locales/lang/en.json"
+import lang_ja from "../../../../locales/lang/ja.json"
 import lang_zhCN from "../../../../locales/lang/zh-CN.json"
 import settings_en from "../../../../locales/settings/en.json"
 import shortcuts_en from "../../../../locales/shortcuts/en.json"
@@ -28,4 +30,8 @@ export const defaultResources = {
     lang: lang_zhCN,
     common: common_zhCN,
   },
+  ja: {
+    lang: lang_ja,
+    common: common_ja,
+  },
 }
diff --git a/src/renderer/src/env.d.ts b/src/renderer/src/env.d.ts
index 6db251e83..06142aad0 100644
--- a/src/renderer/src/env.d.ts
+++ b/src/renderer/src/env.d.ts
@@ -2,3 +2,4 @@
 declare const APP_VERSION: string
 declare const APP_NAME: string
 declare const RELEASE_CHANNEL: string
+declare const I18N_COMPLETENESS_MAP: Record<string, number>
diff --git a/src/renderer/src/modules/entry-column/components/mark-all-button.tsx b/src/renderer/src/modules/entry-column/components/mark-all-button.tsx
index dbc0690ff..1917030b2 100644
--- a/src/renderer/src/modules/entry-column/components/mark-all-button.tsx
+++ b/src/renderer/src/modules/entry-column/components/mark-all-button.tsx
@@ -1,7 +1,5 @@
-import { PopoverPortal } from "@radix-ui/react-popover"
 import { ActionButton, Button, IconButton } from "@renderer/components/ui/button"
 import { Kbd, KbdCombined } from "@renderer/components/ui/kbd/Kbd"
-import { Popover, PopoverContent, PopoverTrigger } from "@renderer/components/ui/popover"
 import { RootPortal } from "@renderer/components/ui/portal"
 import { HotKeyScopeMap } from "@renderer/constants"
 import { shortcuts } from "@renderer/constants/shortcuts"
@@ -176,65 +174,6 @@ const ConfirmMarkAllReadInfo = ({ undo }: { undo: () => any }) => {
   )
 }
 
-/**
- * @deprecated
- */
-export const MarkAllReadPopover = forwardRef<HTMLButtonElement, MarkAllButtonProps>(
-  ({ filter, className, which = "all", shortcut }, ref) => {
-    const [markPopoverOpen, setMarkPopoverOpen] = useState(false)
-
-    const handleMarkAllAsRead = useMarkAllByRoute(filter)
-
-    return (
-      <Popover open={markPopoverOpen} onOpenChange={setMarkPopoverOpen}>
-        <PopoverTrigger asChild>
-          <ActionButton
-            shortcut={shortcut ? shortcuts.entries.markAllAsRead.key : undefined}
-            tooltip={
-              <span>
-                Mark
-                <span> </span>
-                {which}
-                <span> </span>
-                as read
-              </span>
-            }
-            className={className}
-            ref={ref}
-          >
-            <i className="i-mgc-check-circle-cute-re" />
-          </ActionButton>
-        </PopoverTrigger>
-        <PopoverPortal>
-          <PopoverContent className="flex w-fit flex-col items-center justify-center gap-3 !py-3 [&_button]:text-xs">
-            <div className="text-sm">
-              <Trans
-                i18nKey="mark_all_read_button.mark_as_read"
-                values={{
-                  // @ts-expect-error https://www.i18next.com/overview/typescript#type-error-template-literal
-                  // should be fixed by using `as const` but it's not working
-                  which: commonT(`words.which.${which}`),
-                }}
-              />
-            </div>
-            <div className="space-x-4">
-              <IconButton
-                icon={<i className="i-mgc-check-filled" />}
-                onClick={() => {
-                  handleMarkAllAsRead()
-                  setMarkPopoverOpen(false)
-                }}
-              >
-                Confirm
-              </IconButton>
-            </div>
-          </PopoverContent>
-        </PopoverPortal>
-      </Popover>
-    )
-  },
-)
-
 export const FlatMarkAllReadButton: FC<MarkAllButtonProps> = (props) => {
   const t = useI18n()
 
diff --git a/src/renderer/src/modules/feed-column/header.tsx b/src/renderer/src/modules/feed-column/header.tsx
index dcdbd90a1..ff75cc2e1 100644
--- a/src/renderer/src/modules/feed-column/header.tsx
+++ b/src/renderer/src/modules/feed-column/header.tsx
@@ -6,6 +6,7 @@ import { ActionButton } from "@renderer/components/ui/button"
 import { Popover, PopoverContent, PopoverTrigger } from "@renderer/components/ui/popover"
 import { ProfileButton } from "@renderer/components/user-button"
 import { useNavigateEntry } from "@renderer/hooks/biz/useNavigateEntry"
+import { useI18n } from "@renderer/hooks/common"
 import { stopPropagation } from "@renderer/lib/dom"
 import { cn } from "@renderer/lib/utils"
 import { m } from "framer-motion"
@@ -53,7 +54,6 @@ export const FeedColumnHeader = memo(() => {
             }}
           >
             <Logo className="mr-1 size-6" />
-
             {APP_NAME}
           </div>
         </LogoContextMenu>
@@ -80,10 +80,11 @@ const LayoutActionButton = () => {
     width: !feedColumnShow ? "auto" : 0,
   })
 
+  const t = useI18n()
   return (
     <m.div initial={animation} animate={animation} className="overflow-hidden">
       <ActionButton
-        tooltip="Toggle Sidebar"
+        tooltip={t("app.toggle_sidebar")}
         icon={
           <i
             className={cn(
@@ -103,6 +104,7 @@ const LayoutActionButton = () => {
 const LogoContextMenu: FC<PropsWithChildren> = ({ children }) => {
   const [open, setOpen] = useState(false)
   const logoRef = useRef<SVGSVGElement>(null)
+  const t = useI18n()
 
   return (
     <Popover open={open} onOpenChange={setOpen}>
@@ -120,7 +122,7 @@ const LogoContextMenu: FC<PropsWithChildren> = ({ children }) => {
           onClick={() => {
             navigator.clipboard.writeText(logoRef.current?.outerHTML || "")
             setOpen(false)
-            toast.success("Copied to clipboard")
+            toast.success(t.common("app.copied_to_clipboard"))
           }}
           className={cn(
             "relative flex cursor-default select-none items-center rounded-sm px-1 py-0.5 text-sm outline-none",
@@ -129,7 +131,7 @@ const LogoContextMenu: FC<PropsWithChildren> = ({ children }) => {
           )}
         >
           <Logo ref={logoRef} />
-          <span>Copy Logo SVG</span>
+          <span>{t("app.copy_logo_svg")}</span>
         </button>
       </PopoverContent>
     </Popover>
diff --git a/src/renderer/src/modules/settings/tabs/general.tsx b/src/renderer/src/modules/settings/tabs/general.tsx
index 0025fa0e3..de7ed2e76 100644
--- a/src/renderer/src/modules/settings/tabs/general.tsx
+++ b/src/renderer/src/modules/settings/tabs/general.tsx
@@ -221,11 +221,16 @@ export const LanguageSelector = () => {
           <SelectValue />
         </SelectTrigger>
         <SelectContent position="item-aligned">
-          {currentSupportedLanguages.map((lang) => (
-            <SelectItem key={lang} value={lang}>
-              {langT(`langs.${lang}` as any)}
-            </SelectItem>
-          ))}
+          {currentSupportedLanguages.map((lang) => {
+            const percent = I18N_COMPLETENESS_MAP[lang]
+
+            return (
+              <SelectItem key={lang} value={lang}>
+                {langT(`langs.${lang}` as any)}{" "}
+                {typeof percent === "number" ? (percent === 100 ? null : `(${percent}%)`) : null}
+              </SelectItem>
+            )
+          })}
         </SelectContent>
       </Select>
     </div>
diff --git a/tsconfig.node.json b/tsconfig.node.json
index 4203d84c0..35ccca4e3 100644
--- a/tsconfig.node.json
+++ b/tsconfig.node.json
@@ -9,7 +9,7 @@
     "src/env.ts",
     "./src/hono.ts",
     "src/shared/src/global.d.ts",
-    "configs/vite.render.config.ts",
+    "configs/*",
     "./scripts/**/*"
   ],
   "compilerOptions": {