かい

The particle かい is an informal question marker used to turn a statement into a yes/no question. It is predominantly used by male speakers and carries a soft, friendly, or caring tone, making it less blunt than using plain か in casual speech.

Basic usage

かい attaches to the end of a sentence in plain form to ask a yes/no question in a gentle way.

Tone and nuance

In casual speech, ending a question with か alone can sound blunt or interrogative (like a police officer questioning someone). Using かい softens the question, giving it a warm, approachable feel. It is used when speaking to someone younger, a close friend, or someone of equal or lower social status.

With nouns and na-adjectives

With nouns and na-adjectives, だ is typically dropped before かい, or なの is inserted for emphasis or clarification.

Comparison with か and の

• か (casual): Can sound blunt or sharp –
  いく行くかきごう？

  You going?
• かい: Softer and friendlier –
  いく行くかいきごう？

  Are you going?
• の: Gender-neutral casual question –
  いく行くのきごう？

  Are you going?

かい is only used for yes/no questions. For questions with interrogative words (who, what, where, etc.), だい is used instead (e.g. どこにいく行くんだいきごう？).