Japanese Brand Voice Guide:
Style Rules That Keep SaaS Localization Consistent Across Teams

TL;DR

Key Takeaways

• An English style guide cannot substitute for a Japanese brand voice guide — it does not address honorific level, script choice, sentence-final form, or punctuation conventions unique to Japanese.
• Honorific level must be specified with examples, not adjectives — "warm but professional" is not actionable in Japanese. Concrete sentence examples at the correct level are.
• The katakana policy must list key terms explicitly — blanket rules ("use katakana for foreign terms") produce errors because some terms have a kanji standard and some do not.
• 40–60 characters per sentence is the practical target for Japanese B2B brand copy — longer sentences accumulate subordinate clauses that push the predicate too far.
• Passive voice is not always formal — Japanese uses passive for politeness in some contexts and active for clarity in others; the guide must specify when each applies.
• Second-person address has at least four options (あなた, お客様, 御社, ユーザー) and the correct choice depends on surface and context — the guide must map each surface.

What a Japanese Brand Voice Guide Must Contain That English Guides Don't

English brand voice guides typically address tone (friendly, authoritative, direct), vocabulary (plain language, no jargon), sentence structure (short and active), and things to avoid (passive constructions, filler phrases). These are useful for English translators and writers. They are insufficient for Japanese for a precise reason: Japanese has grammatical features that English does not, and those features carry brand signal whether you specify them or not.

When a translator opens a piece of Japanese copy without a brand voice guide, they make default decisions on: the honorific ending attached to every sentence, whether a borrowed term is written in katakana or translated into kanji, how to punctuate dialogue and emphasis, how long to make sentences before breaking them, and what word to use for "you." Every one of those decisions is visible to a Japanese reader and contributes to the brand's perceived register. Leave them unspecified and the brand voice is determined by each translator's individual default — which produces a patchwork across translators, tools, and surfaces.

A complete Japanese brand voice guide contains sections that have no English equivalent:

• Honorific level specification — the position on the です/ます spectrum, with sentence examples at the target level and examples of levels to avoid.
• Script choice policy — kanji, katakana, or hiragana per key term, with a term list rather than a blanket rule.
• Sentence-final form rules — whether the brand ends sentences in polite forms (です/ます), plain forms (だ/である), or nominalizations (〜こと, 〜もの).
• Punctuation conventions — 「」 vs "" for quotations, 。handling, ・ as bullet separator.
• Sentence length target — character count per sentence for the primary copy surfaces.
• Forbidden expressions list — phrases that are technically correct but tonally wrong for this brand.
• Passive vs active voice policy — when each applies and why.
• Second-person address map — which form to use on which surface.

Honorific Level Decision: Specifying the です/ます Spectrum

The first and most impactful dimension of Japanese brand voice is honorific level — specifically, where the brand sits on the です/ます spectrum. This is not the same as formality in English. English uses vocabulary and sentence structure to signal formality. Japanese uses grammatical endings that attach to every sentence, so the honorific level decision affects every piece of copy the brand produces.

The practical spectrum for B2B SaaS runs from ultra-formal (でございます endings, 貴社 for "your company," elaborate set phrases like 誠にありがとうございます) to accessible-professional (standard です/ます, お客様 for the user, active constructions) to casual (plain forms, フレンドリー tone, second-person pronouns). Very few SaaS companies should sit at the ultra-formal end — it reads as stiff and creates distance in a product context. Very few should sit at the casual end for B2B — it reads as disrespectful of the organizational relationship.

The useful specification for most B2B SaaS brands is accessible-professional, but that descriptor is not actionable without examples. The guide should include:

The guide should specify not just which endings to use but which vocabulary markers belong at the target level. At accessible-professional: お客様 (not あなた, not 貴殿); 御社 only in formal sales documents (not in product UI); ご連絡 rather than 連絡 for contact-related phrases; but plain nouns (機能, 設定, 料金) rather than their formal equivalents throughout.

The Katakana Policy: Rules for Script Choice Per Term

Japanese B2B copy mixes three scripts — kanji, hiragana, and katakana — and borrowed technical terms can appear in any of them. The brand voice guide's katakana policy must answer: for each key term used in the product, which script form is approved? A blanket rule ("use katakana for all English-origin terms") produces errors because some borrowed terms have a kanji standard in Japanese business usage and using katakana signals foreign unfamiliarity.

The katakana policy should be a term list, not a rule. The list specifies the approved form for each term with the reason (kanji standard exists / no kanji equivalent / brand name uses katakana). It also lists forbidden alternatives — for instance, if the brand uses ダッシュボード, the list explicitly marks 制御盤 and 管理画面 as non-approved alternatives, even though 管理画面 is technically a reasonable description of a dashboard page.

Punctuation Rules in Japanese Brand Copy

Japanese punctuation has conventions that differ from Western standards, and brand copy that applies Western punctuation rules to Japanese text reads as unlocalized even when the words are correct. The brand voice guide should specify the following punctuation decisions.

Quotation marks: Japanese uses 「」(single corner brackets) for standard quotations and 『』(double corner brackets) for quotations within quotations or for book and product titles. Using Western double quotes ("") in Japanese body copy reads as typographically foreign. The exception is technical strings, variable names, or UI labels that must be reproduced literally — those may be wrapped in Western quotes or backticks per convention.

Ideographic full stop: Japanese uses 。(U+3002) rather than a Western period at sentence end. This should be handled automatically by the font and input method, but should be explicitly documented because MT output occasionally produces Western periods in Japanese text, and the QA rule should catch it.

The interpunct (・) as a separator: Japanese uses ・(U+30FB) rather than a bullet point or slash when listing items inline. ・is also used in foreign names written in katakana (エアー・ビーアンドビー rather than エアービーアンドビー). The guide should specify whether the brand uses ・ for inline lists and how it handles Western proper nouns in katakana.

Parenthetical notes: Japanese uses （）(fullwidth parentheses, U+FF08 / U+FF09) rather than Western half-width parentheses. Using half-width () in Japanese body copy creates inconsistent character width that Japanese typographers specifically avoid.

Sentence Length: The 40–60 Character Rule

Japanese sentence length is a more precise specification than English sentence length because Japanese characters are uniformly wide and the sentence-final predicate position creates a specific readability effect: as sentences grow longer, the reader must hold more information in memory before reaching the predicate that determines the meaning of everything that preceded it.

A practical target for Japanese B2B brand copy is 40–60 characters per sentence. Below 30 characters, sentences feel abrupt and telegraphic — appropriate for UI microcopy but not for explanatory or marketing copy. Above 70 characters, sentences accumulate subordinate clauses that delay the predicate, requiring readers to hold more in working memory than is comfortable for a brand context.

Forbidden Expressions List

Every Japanese brand voice guide needs a forbidden expressions list — phrases that are technically correct Japanese but that read as generic, robotic, or tonally wrong for the brand. The most common offenders in SaaS localization come from two sources: set phrases that MT and inexperienced translators default to, and direct translations of English phrases that produce grammatically correct but socially awkward Japanese.

The most overused set phrase in Japanese SaaS copy is ご利用いただきありがとうございます — thank you for using our service. It appears at the top of every notification email, every onboarding screen, and every support message. It is not wrong. It is so standardized that it has become invisible, and in excess it signals that no one thought carefully about the opening of this communication. The guide can specify: use once per communication maximum, only at the start of formal transactional emails; not in product UI; not in notification subjects.

Passive vs Active Voice Policy

Japanese uses passive voice for structural reasons that English does not — specifically, to soften directives and to describe processes from the object's perspective as a politeness move. This makes the passive-vs-active decision in Japanese brand copy more nuanced than its English equivalent.

The practical rule for most SaaS brands is: use active voice in product UI (button labels, success messages, instructional copy) and in marketing copy where the brand wants to signal confidence and clarity. Use passive in situations where the brand is reporting on a process that happened to the user's data or account (データが処理されました — the data was processed — rather than システムがデータを処理しました — the system processed the data).

The exception is error messages and warnings, where passive voice is often the appropriate choice because it describes what happened without implying user error: ファイルを読み込めませんでした (the file could not be loaded) is more neutral than システムがファイルを読み込めませんでした (the system could not load the file).

Person and Number: How to Handle "You" Across Product Surfaces

Japanese avoids explicit second-person pronouns far more than English — good Japanese copy often omits the subject entirely, relying on context. When a second-person reference is necessary, the choice among あなた, お客様, 御社, and ユーザー is not a preference but a register decision, and each carries different social meaning.

The brand voice guide should map second-person address to surface type:

• Product UI (app surfaces): Omit second-person pronoun where possible. When unavoidable, ユーザー or the user's name if personalization is available. Never あなた in B2B product UI.
• Marketing and onboarding copy: お客様 — respectful, appropriate for addressing a prospective or new customer. Warm without being informal.
• Support and transactional email: お客様 for direct address; 御社 when referring to the customer's company in context (御社のアカウントについて — regarding your company's account).
• Formal sales documents and contracts: 御社 for the customer's company; 貴社 in written (not email) formal documents. These two are not interchangeable: 御社 is spoken and email; 貴社 is written formal only.

Building the Guide: Sections, Format, and Review Process

A Japanese brand voice guide should be a working document, not a reference document. Working means it is short enough to be read and remembered, structured with tables and examples rather than paragraphs, and versioned so changes are traceable. The recommended structure:

1. Brand voice statement in Japanese — one or two sentences describing the brand's Japanese identity, written at the target register. This is the calibration sentence every translator should read before starting.
2. Honorific level specification — the spectrum position, with three target-level examples and two out-of-range examples (one too formal, one too casual).
3. Approved term list — the katakana/kanji policy expressed as a table: term, approved form, forbidden alternatives, notes.
4. Punctuation rules — quotation marks, sentence-end characters, inline separators, parenthetical style.
5. Sentence length target — character count range for the primary copy surfaces (UI, marketing, help center).
6. Forbidden expressions — table of phrases with reason forbidden and preferred alternative.
7. Voice and register by surface — a table mapping product surface to honorific level, second-person form, and sentence-end convention.
8. Dos and don'ts with examples — five to ten real examples at each level, drawn from the actual product copy.

The review process should involve at minimum one native Japanese speaker who is a professional writer or senior localization reviewer — not just a fluent speaker — because the guide is making style decisions, not correctness decisions, and the distinction requires a trained editorial eye. The guide should be reviewed after every major product update and after any marketing campaign that produced localization requiring judgment calls not covered by the existing rules.

Japanese Brand Voice Guide Checklist

Frequently Asked Questions