Polite (Keitai) vs Plain (Jōtai) Style: Choosing by Situation [JLPT N4]
By Nihongo to Japan · Updated July 3, 2026
Master the subtle differences between polite and plain style to make your Japanese more appropriate.
Polite (Keitai) vs Plain (Jōtai) Style: Choosing by Situation
Japanese has two styles: polite style (ていねい体) = ending in 「です・ます」 (行きます, です); plain style (普通体) = ending in 「だ・plain form」 (行く, だ). The key is choosing the right style by situation and listener: ① polite style for formal, toward superiors/first meetings/business/strangers (first meetings, business, toward teachers: 行きました, です); ② plain style for close relations, toward friends/family/diaries/papers (LINE with friends, family, diaries: 行った, だ). ⚠️ Important principle: the style must be consistent within one text/conversation, not mixed (mixing polite and plain sounds unnatural). ⚠️ Papers/reporting use plain (である style); diaries, friend conversations use plain.
🧠 Core nuance: by listener and situation, choose polite or plain
The core is choosing the right style by listener, situation, text type, and keeping it consistent throughout: ① polite style (です・ます) — polite, formal, for: first meetings, business, toward superiors/bosses/clients/strangers, formal occasions, letters to teachers (行きます, 食べました, 学生です). Expresses respect, keeping distance; ② plain style (普通形・だ) — close, casual, for: between friends, family, partners, diaries, novels, papers (papers use 「である style」), inner monologue (行く, 食べた, 学生だ). Expresses intimacy or objectivity. ⚠️ Core principle: the style must be consistent — within one text or conversation, don't mix polite and plain (✗ 行きました。そして食べた = mixed, unnatural). ⚠️ Judging the situation: uncertain, first meeting, formal → use polite (safer, courteous); familiar, close, written argument → plain. ⚠️ Papers, news, reports use 「である style」 (である, だ, an objective formal plain style); diaries, friend conversations use 「だ style」 (plain). The foundation of appropriate N4 expression.
📌 Style Comparison
| Style | Ending | Situation | Example |
|---|---|---|---|
| polite (ていねい体) | です・ます | formal, toward superiors/business/strangers | 行きます/学生です |
| plain (普通体) | だ・plain form | close, friends/family/diaries | 行く/学生だ |
| である style | である・だ | papers, reporting (objective formal) | 〜である |
💬 Example Sentences
- (business first meeting) はじめまして、田中と申します。(Nice to meet you, I'm Tanaka.) — polite (formal)
- (friend LINE) 今日、暇? 一緒に行く?(Free today? Want to go together?) — plain (close)
- (letter to a teacher) 昨日は学校に行きました。先生に褒められました。(Yesterday I went to school. I was praised by the teacher.) — consistent polite
- (diary) 今日は疲れた。早く寝よう。(I'm tired today. Let's sleep early.) — plain (diary)
- (paper) この結果から、〜であると考えられる。(From this result, it can be considered that 〜.) — である style (paper)
🔄 Compare: polite vs plain vs である style vs honorific/humble
| Style | Nuance | Situation |
|---|---|---|
| polite (です・ます) | polite, keeping distance | business, toward superiors, strangers |
| plain (普通体) | close, casual | friends, family, diaries |
| である style | objective, argumentative | papers, reporting |
| honorific/humble | higher respect | toward clients, bosses (above polite) |
⚠️ Common Mistakes
- Keep the style consistent: within one text/passage, don't mix polite and plain (✗ 行きました。食べた), it sounds unnatural.
- Formal occasions use polite: first meetings, business, toward superiors use polite (です・ます); ✗ plain (rude).
- Papers use である style: papers, reporting use である style (である, だ), not です・ます (colloquial feel).
- Uncertain → polite: when uncertain of the relationship or situation, polite is safer and courteous.
💡 Nuance & When to Use
Japanese has polite style (です・ます, polite formal) and plain style (普通形・だ, close casual). Polite for toward superiors/business/first meetings/strangers; plain for friends/family/diaries; papers use である style. ⚠️ Core principle: keep the style consistent, don't mix. Judging: uncertain or formal use polite (safer); close or written argument use plain. The foundation of appropriate N4 expression. A must.
🎯 JLPT Exam Tips
- N4 core: polite (です・ます, toward superiors/business/strangers), plain (普通形・だ, friends/family/diaries), である style (papers/reporting).
- Core principle: keep the style consistent, don't mix polite and plain!
- Judging the situation: uncertain or formal → polite (safer, courteous); close or written argument → plain/である style.
🖊️ Practice Quiz
Q1. Which register should be used in a first-meeting business scene?
(A) plain (だ/plain form)
(B) polite (ます・です)
(C) either is the same
(D) only the sentence-end need be polite
Q2. What's a natural register for a LINE message to a friend?
(A) polite (ます・です)
(B) plain (plain form/だ)
(C) either is fine
(D) must be polite
Q3. 「今日は学校に行き___。先生に褒め___。」(a formal diary, consistently polite)
(A) た、られた (B) ました、られました (C) た、られました (mixed → wrong) (D) both A and B
Q4. Which is correct as a paper's sentence-ending?
(A) 〜だと思います。(ます → colloquial)
(B) 〜であると考えられる。(plain, academic written style)
(C) 〜だよ。(colloquial, informal)
(D) 〜ですかね。(too soft)
Q5. What happens if you mix the polite and plain registers?
(A) it sounds more natural
(B) it sounds unnatural (the style consistency breaks)
(C) it's recommended in papers
(D) you can speak faster
Answer Key
1. (B) polite (ます・です) ── a first-meeting business scene is the most formal → always use the polite register. Plain is only for intimate relationships.
2. (B) plain (plain form/だ) ── a LINE message to a friend naturally uses the plain register.
3. (B) ました、られました ── a formal diary keeps the register consistent (polite throughout); mixing is wrong.
4. (B) 〜であると考えられる ── papers use the plain, academic written style.
5. (B) ── mixing registers sounds unnatural (it breaks the style consistency).