Plurals

There aren't any. 本 means "book" or "books"; 人 means "person" or "people". Number comes from a counter, a number word, or context — never from the noun itself.

本を買いました — I bought a book. / I bought books. Both. The sentence does not say. 本を三冊買いました — I bought three books.

This is one of the genuine simplifications in Japanese, and the mirror image of the trouble Japanese speakers have with English plurals and articles.

たち — the "and company" suffix

It attaches to people (and pets), and it does not mean "more than one" so much as "this person and their group":

Casual variants: 僕ら bokura, 彼ら karera. Never ✗ 本たち — objects do not take it.

Reduplication

A handful of nouns double up, usually with the 々 repeat mark. This is fossilised vocabulary, not a productive rule:

Note the sound change — hitobito, not hitohito: the second element voices. That is 連濁 rendaku, and it runs through Japanese compounding everywhere.

Words that are already plural-ish

みんな minna everyone · 皆さん minasan everybody (polite) · 全部 zenbu all of it · たくさん takusan a lot · いくつか ikutsuka several.

Where English speakers slip

Saying ✗ 本たち or ✗ 三本たち. Once you have a number or a counter, you already have plurality — adding more is like saying "three bookses".

And in the other direction: because Japanese does not force the choice, you will occasionally not know whether a speaker means one or many. Usually it does not matter. When it does, they will tell you.

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