Grammar Point
particle
prt 
familiar language
fam 
かい

yes?, no?, isn't it?, is it?

used at sentence-end; indicates a question (sometimes rhetorical)

Sentence-end Particle かい

The particle かい is used at the end of a sentence to form a yes-no question in informal speech. It is primarily used by male speakers and often conveys a gentle or affectionate tone, especially when used by older men towards younger people or social inferiors.

Verb or い-Adjective informal form + かい

When used with verbs or い-adjectives, かい follows the informal (plain) form of the word.

Are you going to eat?

Did you read the book?

い-Adjective informal form + かい

When used with い-adjectives, the particle follows the informal present or past form.

Is it cold?

Was it delicious?

な-Adjective stem or Noun + かい

When used with な-adjectives or nouns in the present tense, the copula だ is usually omitted before かい.

Are you free?

Is this your bag?

Note

かい is strictly for yes-no questions and cannot be used with question words like なに (what) or だれ (who). It is an informal counterpart to the polite particle か, but it is less blunt than simply using a rising intonation. In modern Japanese, it is less common among younger generations.

Words: 
かい
かえ
Radicals of radicals