Formal Japanese isn't a separate language — it's the same Japanese with a different choice of verbs, sentence endings, and personal pronouns. This guide explains what changes between casual and formal Japanese, with a focus on the writing situations that non-native business writers actually face.
The four registers of Japanese writing
- Casual (くだけた表現): friends, family, social media. da / dayo endings. Almost never used in business.
- Polite-neutral (です・ます): the default register for business writing between peers. Most blog posts and marketing copy live here.
- Polite-formal (ですます + 接頭辞): adds honorific prefixes (o-, go-) and slightly more elevated verbs. Email to external contacts in established relationships.
- Highly formal (尊敬語＋謙譲語＋クッション): full honorific machinery — respectful verbs for the other party, humble verbs for yourself, cushion phrases. First contact, apology, formal proposals.
What changes between registers
Sentence endings
- Casual: 食べる (to eat)
- Polite-neutral: 食べます
- Polite-formal: 召し上がります (someone else eating) / いただきます (you eating)
Personal pronouns
- Casual: 俺 / 僕 / あたし
- Polite: 私 (watashi)
- Formal: わたくし (watakushi)
For your company: 弊社 (formal) vs 当社 (internal only) vs うち (casual).
Honorific prefixes
Formal writing adds o- and go- to nouns referring to the other party:
- 意見 (opinion) → ご意見
- 名前 (name) → お名前
- 会社 (company) → 御社 / 貴社
Cushion phrases
Formal Japanese pads requests and statements with formulaic softeners:
- 恐れ入りますが (I'm sorry to ask, but…)
- お忙しいところ恐縮ですが (sorry to bother you when you're busy)
- 誠に勝手ながら (with all due deference)
- ご多忙のところ大変恐縮ですが (even more deferential version)
Which register to use, by situation
| Situation | Register |
|---|---|
| Slack to a peer | Polite-neutral |
| Email to a peer | Polite-neutral |
| Email to your manager | Polite-formal |
| Email to an existing client | Polite-formal |
| Cold outreach | Highly formal |
| Apology to a client | Highly formal |
| Contract / legal document | Highly formal (teineigo + kenjogo, no sonkeigo) |
| Marketing landing page | Polite-neutral with occasional formal lift |
Common mistakes non-native writers make
1. Over-using sonkeigo on yourself. Sonkeigo is for the other party. Saying 私はおっしゃいました (I said, using respectful form for "say") is grammatically incorrect.
2. Stacking honorifics. ご確認頂戴いたします stacks two humble verbs. One is enough.
3. Mixing registers within an email. Opening with a highly formal greeting and closing with a casual よろしくfeels jarring to a Japanese reader.
4. Direct translation of English idioms. "Have a nice weekend" as 良い週末をお過ごしください works, but "Looking forward to hearing from you" as a direct translation often comes out awkward — Japanese uses お返事をお待ちしております.
Tools that help
A business-specific Japanese translator with register dropdowns solves most of these mistakes automatically. The author picks the situation ("cold outreach", "apology email", "internal memo"), and the tool applies the right register, the right cushion phrases, and the right opening / closing lines.
BizHonyaku exposes these as a recipient/relationship dropdown. Generic translators (Google, DeepL) translate the literal meaning and rely on you to know the register. For business email and client-facing writing, the dropdown is the difference between "correct Japanese" and "Japanese that feels right".