文末表現N4
〜だい／〜かい
...? (male casual question particle)
Structure
普通形 + かい；N/な形 + だい
Explanation
Sentence-final question particles in male casual speech. かい follows plain verbs/い-adjectives; だい follows nouns/な-adjectives (and past verbs). Friendly and informal (どこへ行くんだい？ 元気かい？).
Examples
君、元気かい？
Hey, how are you doing?
休みの日はどこへ行くんだい？
Where do you go on your days off?
Note
かい/だい are male casual particles used with close friends or juniors, never in formal settings. Women use 〜の？ etc.