If you read why AI translation fails for Japanese, you saw register drift listed as one of the most common failure modes. This article goes deeper: what the registers are, how to pick one for your app, and how to apply it consistently.
For broader context see the complete guide to Japanese app localization.
What "Register" Means in Japanese
English has politeness levels — "Please log in" vs. "Log in" vs. "Log in, jerk." But politeness in English is mostly about word choice. In Japanese, politeness is grammatical. Verbs change form, particles change usage, sometimes the entire word changes. You do not get to write a Japanese sentence without picking a register.
For app copy, four registers cover almost every case.
The Four Registers of App Copy
1. Polite-neutral (です/ます form)
The default register for most consumer apps. Friendly, respectful, professional, not stiff.
Pattern: verbs end in 「〜ます」, copula is 「です」.
ログインしてください。 (Please log in.) ファイルを保存しました。 (File has been saved.) 通知を受け取りますか？ (Receive notifications?)
When to use: most consumer productivity apps, e-commerce, education, health, anything where the user is an adult interacting with a brand they don't know personally.
2. Plain (だ/である form, or no copula)
Used in note apps, dev tools, technical content, and any UI where brevity beats warmth.
Pattern: verbs in plain form 「〜する」, copula is 「だ」 or omitted.
ログインする (Log in) 保存完了 (Saved) 通知を受け取る (Receive notifications)
When to use: developer tools (GitHub-style apps), note-taking apps where conciseness is a value (Notion, Bear), dashboards, terminal-like interfaces.
3. Honorific (敬語 / keigo)
Reserved for premium, finance, healthcare, customer-service contexts.
Pattern: 「お/ご」 prefixes, 「いただく」「いたします」「させていただく」 verbs, occasionally 「お客様」 for "you/customer."
ログインしていただけます。 (You may log in. — humble form makes it about us enabling you.) ファイルを保存いたしました。 (File has been saved. — humble version of する.) 通知をご利用いただけます。 (Notifications are available for your use.)
When to use: banking and fintech, insurance, healthcare, legal, business B2B apps, premium subscription services. Not suitable for casual consumer apps — it sounds suffocating.
4. Casual / friendly
Used by social apps, dating apps, Gen Z–targeting apps.
Pattern: verbs in plain form, 「〜よ」「〜ね」「〜だよ」 endings, sometimes 「〜しよう」 instead of 「〜しましょう」.
ログインしよ！ (Let's log in!) 保存できたよ (Saved!) 通知を受け取る？ (Receive notifications?)
When to use: social/community apps, dating apps, casual gaming, apps explicitly targeting users under 30.
How to Pick the Right Register
Three questions, in order:
Q1: Who is the user, and how do they expect to be addressed?
- A working adult installing a banking app expects keigo from the brand.
- A teenager installing a social app expects to be talked to like a friend.
- A freelancer installing a productivity tool expects polite-neutral.
If your user demographic is mixed, default to polite-neutral. It is the register that offends nobody.
Q2: What is your brand voice?
A meditation app and a productivity app might both use polite-neutral, but they diverge on warmth. Encode this in your tone document — see the iOS/Android step-by-step guide for what to put in it.
Q3: What is the screen-level emotional context?
Even within a polite-neutral app, certain screens benefit from register adjustment:
- Error screens sometimes shift slightly more humble: 「申し訳ございません。再度お試しください。」 ("We apologize. Please try again.")
- Celebration screens sometimes shift slightly more casual: 「お疲れさま！」 ("Good work!")
- Sensitive actions like account deletion often shift more formal: 「本当に削除されますか？」
The point is not to use four registers in one app. The point is to consistently use one base register with calibrated shifts at emotional peaks.
Common Mistakes
Mistake 1: Defaulting to honorific because "more polite is safer"
We see this constantly with Western teams whose first instinct is "let's pick the most respectful version." Honorific in a casual fitness app sounds like a wedding hall greeting card. It is jarring, not reassuring.
Mistake 2: Mixing 「あなた」 with honorific verbs
「あなた」 (you) is grammatically valid but feels distant in honorific contexts. Honorific Japanese drops the subject or refers to the user as 「お客様」.
❌ あなたは設定をご確認いただけます。 ✅ 設定をご確認いただけます。
Mistake 3: Inconsistent endings within the same screen
A modal dialog with three lines, three different registers:
❌ アカウントを削除しますか？ 削除すると元には戻せません。 削除する／キャンセル
The first two are polite-neutral 「ます」. The third is plain. Most users will not be able to articulate why this feels off, but they will feel it. The fix: pick one and stay.
Mistake 4: Using keigo for buttons
Keigo verbs are long. Buttons are short. They are physically incompatible.
❌ Button label: ご確認いただく ✅ Button label: 確認
In keigo apps, the body copy can use keigo while the buttons use the plain verb form. This is a real convention — finance app buttons say 「確認」 even when the surrounding copy says 「ご確認いただけます」.
Mistake 5: Direct translation of "you/your"
In English: "Save your changes." In Japanese, drop "your":
❌ あなたの変更を保存する ✅ 変更を保存
If you ever see 「あなたの」 in your app's UI strings outside a tutorial that's literally explaining a personal pronoun, it's almost certainly wrong.
A Worked Example: Same Onboarding Screen, Four Registers
Source English:
Welcome. Let's set up your profile. What should we call you? [Continue]
Polite-neutral (default for most consumer apps)
ようこそ。 プロフィールを設定しましょう。 お名前を教えてください。 [次へ]
Plain (productivity / dev tool)
ようこそ プロフィールを設定する 名前を入力 [次へ]
Honorific (premium / finance)
ようこそお越しくださいました。 プロフィールの設定にお進みください。 お名前をご入力ください。 [次へ進む]
Casual (social / Gen Z)
ようこそ！ プロフィールを作ろう なんて呼べばいい？ [はじめる]
All four are correct. The difference between the right one and the wrong one is the difference between an app that gets paid for and an app that gets uninstalled.
Register and Brand Voice in Practice
A few examples from real Japanese apps to anchor what each register looks like at scale:
- メルカリ (Mercari) — polite-neutral with warm, friendly inflections. Buttons in plain form. Body in です/ます.
- PayPay — polite-neutral with finance-tinged shifts to keigo for sensitive screens. Strong consistency.
- LINE — polite-neutral for system messaging, conversational casual for community-flavored UI.
- Money Forward (家計簿) — polite-neutral with mild keigo for premium-tier copy.
- TikTok JP — casual throughout, calibrated to its user base.
If you have a Japanese app you admire, find it on the App Store, install it, and read every screen. The tone document for your localization should reference 2–3 of these as "we want to sound like X, not Y."
A Quick Self-Check Before Shipping
Before you ship Japanese strings, run this check on a random sample of 30 UI strings:
- Does every sentence in the same screen use the same register?
- Is there any 「あなた」 or 「あなたの」 that could be removed?
- Are the buttons short, even if the surrounding copy is keigo?
- If you read the strings aloud, do they sound like a single person speaking?
If yes to all four, the register is calibrated.
Where to Go Next
- Why AI Translation Fails for Japanese App Copy
- The 12 Most Common Mistakes in Japanese App Localization
- Japanese UX Writing: Microcopy That Feels Native
- How to Make App Copy Sound Native in Japanese
We help teams pick and apply a Japanese register consistently across their app, including writing the tone document referenced above. Contact us if you want a register audit of your existing app.