かい
Question marker
Structure
［い］Adjective + （の） + かい
Noun + （なの） + かい
［な］Adjective + （なの） + かい
Explanation
The sentence-ending particle かい is used to form a question in Japanese. While it often functions like a single unit, it is technically a blend of the question marker か and the particle い. This particle, い, adds a nuance similar to ね or よ and is predominantly used by male speakers in casual conversation.
かい is typically placed right after the part of the sentence being questioned. With verbs and い-Adjectives, the particle の can be placed before かい. With な-Adjectives and nouns, なの can be used in the same position. Because かい is very informal, however, this の (or なの) is often left out.
- このゲームをやりたいのかい？You wanna play this game?
- あの映画は面白いのかい？Is that movie any good?
- あの先生は親切なのかい？Is that teacher kind?
- 君はお医者さんなのかい?Are you a doctor?
When の (or なの) is used, it can be contracted to ん (or なん). This contraction works just like it does in the more formal のです and なのです grammar patterns.
- もう家に帰りたいんかい？You want to go home already?
- 日本人なんかい。中国人だと思ってた。You're Japanese? I was sure you were Chinese.
While not a strict rule, かい is most commonly used to ask simple questions that can be answered with a 'yes' or 'no'.
- もう寝てるのかい？Are you asleep already?
Caution
Due to its very informal and direct nature, かい can sometimes come across as accusatory. It is important to be mindful of your tone to avoid being misunderstood.
- また宿題を忘れたんかい。You forgot your homework again, huh?
Fun Fact
The sentence-ending particle い is rarely seen by itself in contemporary Japanese, appearing mostly in fixed expressions like かい or だい. Although it functions somewhat like ね, い is considered quite ぞんざい ('rough' or 'unrefined'), so it should be reserved for use with close friends and never with superiors or elders.
Examples
まだ食べるのかい？
You're still going to eat?
これが彼のプレゼントなのかい？
This is his present?
そんなに嬉しいのかい？
Are you really that happy?
彼女のこと、まだ好きなのかい？
Do you still have feelings for her?
宿題を手伝わないのかい？
Aren't you going to help me with the homework?
一人で全部やりたいのかい？
You want to do it all by yourself?
もう帰っていいのかい？
Is it alright if I head home now?
またゲームをしていたのかい？
Were you playing video games again?
わざわざ雨の中、ここまで歩いてきたのかい？
You mean to say you walked all the way here in the rain?
この映画、面白くないのかい？
You don't find this movie interesting?
謝らなくていいのかい？
Don't you think you should apologize?
せっかくの休みなのに、部屋の掃除だけで本当に平気なのかい？
It's your long-awaited day off, are you really okay with spending it just cleaning your room?