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Japanese grammar

Polite vs plain Japanese: ます and です

Japanese changes the end of the sentence depending on who you are talking to. Friends and family get the plain form (たべる), and teachers, strangers and shop staff get the polite form (たべます). The meaning does not change, and only the last word moves. This guide covers ます, ません, です and the one place politeness never goes.

Examples are written in kana. New to it? Start with the hiragana chart.

In short

  • Choose by audience, not by topic: plain to friends, polite to strangers.
  • ます goes on verbs, です finishes nouns and adjectives.
  • The polite negative swaps ます for ません.
  • Only the final verb carries politeness. A clause before と おもう stays plain.

Talking up — ます

Build polite ます-forms from the い-stem (のむ→のみます); さん honors others' names, と names companions.

Polite verbs are built from the i-STEM: drop the final -u to the い row, then add ます. のむ → のみ + ます. る-verbs just drop る: たべる → たべ + ます. する → します, くる → きます. The MEANING doesn't change — たべる and たべます both mean 'eat'. Only the audience changes. The people you talk about politely wear さん — the everyday 'Mr./Ms.' you attach to someone else's name (たなか → たなかさん), never to your own. When you name who you did it WITH, that person takes と: 「ともだちと のみます」 = I drink with a friend. と joins people to the action; に, which you met marking where something is, never does this job. One more polite word arrives with ます: はい, the polite 'yes'. 「はい、たべます。」 = Yes, I'll eat.

  • たべます

    I eat. (polite)

  • みずを のみます

    I drink water. (polite)

Common mistake

たべるます

Why it's wrong: the る is dropped before ます — たべます, not たべるます

Politely saying no — ません

The polite negative swaps ます for ません: のみます→のみません, the twin of plain ない.

The polite negative swaps ます for ません — same stem, different tail. のみます → のみません. It is the polite twin of plain ない: のまない = のみません.

  • のみません

    I don't drink. (polite)

  • きょうは いきません

    I'm not going today. (polite)

  • ごはんを たべません

    I don't eat rice. (polite)

  • しゃしんを みません

    I don't look at the photo. (polite)

Common mistake

のみますない

Why it's wrong: ません REPLACES ます — you don't stack ない on top of it

です — the noun's polite finish

です politely finishes NOUNS (ねこだ→ねこです), never verbs — たべるです isn't a sentence.

です finishes NOUNS politely, the way だ finishes them plainly: ねこだ → ねこです. です is NOT 'polite だ' you can bolt onto verbs — たべるです is not a sentence. Verbs get ます; nouns get です. Any noun sits in that slot: がくせい (a student), せんせい (a teacher), アメリカじん (an American — a country name plus じん 'person' names the nationality). Place words are nouns too, so あそこ ('over there') takes です — 「じゅぎょうは あそこです」 — and, like any noun, a place can pin down another noun with の: 「あそこの ひと」 is 'the person over there', the same の you know from 「ミカの ほん」.

  • がくせいです

    I'm a student. (polite)

  • たなかさんは せんせいです

    Tanaka is a teacher. (polite)

Common mistake

たべるです

Why it's wrong: verbs take ます, not です — たべます

Who are you talking to?

Japanese picks plain (たべる) or polite (たべます) by WHO you're talking to, not what you mean.

Japanese picks its form by WHO you're talking to, not by what you mean. Friends and family get plain (たべる). Teachers, strangers, and customers get polite (たべます). Same thought, two skins — you choose by audience, every sentence. Even 'yes' has two skins: うん to a friend, and ええ — a soft, warm 'yes' — to anyone you are being polite with, beside the crisper はい.

  • たべる

    I'll eat. (to a friend)

「たべますと おもう」 は ✗ — the quote stays plain

Only the final verb takes ます; whatever sits before と inside the quote stays plain.

Politeness lives on the FINAL verb of the sentence and nowhere else. Whatever you park in front of と stays PLAIN — always, without exception. 「ミカは すしを たべると おもう」 is the casual sentence; speaking politely you change only the last word, to 'omoimasu', and the たべる inside the quotation does not move. 「たべますと おもう」 is not stiff Japanese, it is wrong Japanese. This is why the course taught you plain form first: the quoted clause is the plain sentence you have been building since module 5, and ます is a coat you put on the last word only.

  • ミカは すしを たべると おもう。

    I think Mika will eat sushi.

  • トムは ほんを かうと おもう。

    I think Tom will buy a book.

  • ケンは きょう はたらくと おもう。

    I think Ken will work today.

  • ミカは えきで まつと おもう。

    I think Mika will wait at the station.

  • たなかは ミカに おしえると おもう。

    I think Tanaka will teach Mika.

Common mistake

ミカは すしを たべますと おもう。

Why it's wrong: the clause in front of と is ALWAYS plain — politeness belongs to the last verb only, never inside the quotation: ミカは すしを たべると おもう。

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