Formal Written Japanese: Style Rules for Papers, Reports & Emails (must-read for N2) [JLPT N2]

Content by NTJ Kuma · Nihongo to Japan editorial team · Updated July 27, 2026

“〜である体,” “〜と考えられる,” “〜に他ならない” — the core expressions of N2 written Japanese

How do you turn 「〜だと思います」 into a paper's tone? — rules for converting speech to written style

Told your papers and reports are “too colloquial”? Turn 「〜だと思います」 into 「〜と考えられる」, 「でも」 into 「しかし」, 「すごく」 into 「非常に」 — that's the craft of written style (書き言葉). This guide organizes the core principles of Japanese formal written style, a spoken→written conversion table, and common paper connectives, upgrading your papers, reports, and formal emails from “chat tone” to “professional prose.” (For spoken honorific levels, see 〈register switching〉.)

Core: three principles of written style (である style・de-colloquialize・objective)

Formal written style (papers, reports, formal documents) has three principles:

• ① use the 「である style」 (plain written): end sentences with 「〜である・〜だ・〜と考えられる」, not 「です・ます」 (spoken politeness) nor 「〜だよ・〜だね」 (colloquial).
• ② remove colloquial elements: no contractions (×〜ちゃう→〜てしまう), colloquial words (×すごく→非常に), colloquial connectives (×でも→しかし).
• ③ objective, not addressing a specific reader: avoid the subjective 「私は〜と思う」, prefer the objective 「〜と考えられる・〜と言える」.

In a line: written style = である style ＋ de-colloquialize ＋ objective. Unify throughout; never mix 「である」 and 「です・ます」.

Spoken → Written conversion

Common connectives for papers・reports

Style points for emails・reports

Formal emails and business reports aren't as rigid as papers, but have style rules too:

• Formal email: mostly honorifics ＋ です・ます style (polite to the reader), opening 「お世話になっております」, closing 「よろしくお願いいたします」; avoid colloquial contractions (×〜ちゃって→〜てしまい).
• Reports・proposals: mostly the である style (objective statement), bulleted key points, concise sentences.
• In common: avoid vague colloquialisms (〜かな・〜みたいな), use clear written expressions (〜と考えられる・〜と思われる).

Judge: “addressing the reader” (emails, speeches) → です・ます; “objective statement” (papers, reports) → である. Pick one and unify throughout.

⚠️ Where learners slip up

① Never mix 「である」 and 「です・ます」 within one piece. The most basic, commonest error. Choose the である style and it's 「〜である・〜だ」 throughout; choose the です・ます style and it's 「〜です・〜ます」 throughout — switching midway is a major taboo (×〜である。〜と思います。). Write a paper in である style, a letter to a reader in です・ます style, but within one piece, always unify.

② Leftover colloquial elements give you away. Chinese/English speakers writing Japanese often unconsciously leave colloquialisms — 「でも」「すごく」「〜ちゃう」「〜とか」「やっぱり」「〜みたいな」. All must be swapped in formal writing (でも→しかし, すごく→非常に, 〜とか→〜など). Proofread once and hunt down colloquial words to replace.

③ Over-subjectivity (私は〜と思う) isn't objective enough in a paper. Papers value objectivity; go easy on the subjective assertion 「私は〜と思う」, prefer objective expressions: 「〜と考えられる」 (can be considered), 「〜と言える」 (one can say), 「〜する必要がある」 (there is a need to), 「〜が示唆される」 (suggests). Swap “I think” for “(objectively) it can be considered,” and the argument reads rigorous, professional.

💡 Quick takeaway

Formal written style (papers, reports) comes down to three things: ① である style (sentence-end 〜である・〜と考えられる, no です・ます, no colloquial); ② de-colloquialize (でも→しかし, すごく→非常に, 〜ちゃう→〜てしまう, 〜とか→〜など); ③ objective (less 「私は思う」, more 「〜と考えられる」). Three practical reminders: ① unify the style throughout — pick である or です・ます, never mix; ② hunt colloquial words after writing — でも・すごく・〜とか・やっぱり all get swapped; ③ use written connectives (したがって・しかし・さらに・なお・以上のことから) for structured argument. Choosing the style: objective statement (paper/report) → である, addressing the reader (email/speech) → です・ます. Master this and your Japanese writing rises from “chat” to “professional.” (For spoken honorific levels, see 〈register switching〉.)

❓ Quick FAQ

Q: Should a paper use the 「である style」 or the 「です・ます style」? Can I mix them?

Papers, academic reports, formal documents use the 「である style」 (objective, concise, not addressing a specific reader): 「本稿では〜を論じる」「〜が重要である」「〜と考えられる」. Here です・ます sounds too colloquial, unacademic. But letters, speech drafts, writing to a specific reader, or a school-assigned “polite-style essay” use the 「です・ます style」 (politely addressing the reader). Never mix them — this is the iron rule. Choose the である style and it's である throughout (〜である・〜だ・〜と考えられる); choose the です・ます style and it's です・ます throughout; switching midway (〜である。次に〜と思います。) is a serious style error that loses points. Also, the である style has fittings: avoid contractions (×行っちゃう→行ってしまう), avoid colloquial words (×すごく→非常に, ×でも→しかし), end sentences with 「〜である・〜だ・〜と考えられる・〜と言える」. Trick: objective writing for an unspecified readership → である style; writing that politely addresses the reader → です・ます style, unified throughout.

Q: How do I quickly convert colloquial Japanese to written style?

Three levels of checking, from shallow to deep:

① Swap colloquial vocabulary (most direct): 「でも→しかし」「だから→したがって」「すごく／とても→非常に」「ちょっと→少し」「〜とか→〜など」「やっぱり→やはり」「いろんな→さまざまな」. These are the colloquial words that give you away most; swapping them makes it far more professional.

② Eliminate contractions and colloquial grammar: 「〜てる→〜ている」「〜ちゃう／〜じゃう→〜てしまう」「〜なきゃ→〜なければならない」「〜って→〜という」. Contractions are colloquial markers; written style restores the full forms.

③ Raise objectivity and connection: change the subjective 「私は〜と思う」 to the objective 「〜と考えられる／〜と言える」; use written connectives (したがって・しかし・さらに・なお・一方・以上のことから) to give paragraphs logic.

Practical tip: after writing, read from the top hunting specifically for the three problem types “colloquial words, contractions, over-subjectivity,” and replace one by one. Over time you develop a “written-style sense” and naturally write in written style. This applies to papers, reports, and formal emails (for emails, keep です・ます politeness, but de-colloquialize the rest the same way).

🖊️ Practice Questions (5)

Q1. 論文中「私はこれが重要だと思います」を書面語に直すと？

(A) 私はこれが重要だと思う

(B) これは重要であると考えられる

(C) これは重要ですよ

(D) これはすごく重要

Q2. 「この問題は準備不足___。」(This problem is precisely a lack of preparation — emphatic assertion)

(A) だと思う　(B) に他ならない　(C) にすぎない　(D) でしょう

Q3. 書面語で「でも」を正式に言うと？

(A) だが/しかし　(B) けど　(C) でも　(D) でもね

Q4. 「〜にすぎない」の意味は？

(A) merely ~ / just ~ (weakening)

(B) 絶対に〜 (strong assertion)

(C) precisely ~ / nothing but ~

(D) although ~, but

Q5. 「先行研究___分析した。」(I analyzed based on prior research)

(A) にもとづいて/をもとに　(B) だから　(C) について　(D) によって

Answer Explanations

1. (B) これは重要であると考えられる ── Academic written style: ① avoid 「私は〜と思います」(subjective/colloquial) → use 「〜と考えられる」(it can be considered ~, objective) instead; ② use the である style, not です.

2. (B) に他ならない ── 「この問題は準備不足に他ならない」(this problem is precisely a lack of preparation) = 〜に他ならない means 'precisely ~ / nothing but ~,' a strong assertion. にすぎない (C) means 'merely ~' (weakening), the opposite meaning.

3. (A) だが/しかし ── The written-style 'but' uses しかし (most formal) or だが (written/commentary). でも・けど are colloquial and unsuited to academic written style.

4. (A) merely ~ / just ~ (weakening) ── 「〜にすぎない」(no more than ~) is used to weaken or relativize a statement: 「これは一例にすぎない」(this is merely one example). The opposite of に他ならない (precisely ~, strengthening).

5. (A) にもとづいて/をもとに ── 「先行研究をもとに分析した」(analyzed based on prior research) = をもとに means 'based on ~ / grounded in ~.' にもとづいて is also correct (more formal/written). について means 'about ~,' and によって means 'due to ~ / by ~,' different meanings.

🎯 「Formal Japanese Writing: Papers and Reports」N2 key exam points: