particle N3 common casual
だい — casual masculine question marker (on wh-questions)
だい
Meaning
- …? — a casual, masculine sentence-final marker that turns a wh-question into a friendly or fatherly query
Key sentence
何が欲しいんだい?
What is it you want?
Formation
| Attaches to | Form | Example |
|---|---|---|
| Wh-question (plain, often + ん) + だい | 疑問詞 〜（ん）だい | どこへ行くんだい (where are you going?) |
Examples
一体どうしたんだい?
What on earth happened?
君の名前は何だい?
What's your name?
When you can't use it
- Used with question words (何, どこ, 誰, なぜ). For a yes/no question, the matching masculine form is かい, not だい. Sounds older/fatherly and is common in fiction.
Easily confused with
Notes
- Pairs with かい for yes/no: どこへ行くんだい? ('where are you going?') vs 行くのかい? ('are you going?'). The pair reads as dated, fatherly, or fictional.
See だい in real sentences
Jengo shows だい the way you actually meet it: inside real Japanese sentences, so it sticks instead of staying an abstract rule.
Study it in JengoSources Compiled with reference to A Dictionary of Basic Japanese Grammar.