Koiwai
Koiwai is a Japanese surname. Notable people with the surname include:
- Eichi [Karl Koiwai], American judoka
- Kotori Koiwai, Japanese voice actress
- Kumiko Koiwai, Japanese figure skater
- Sakura Koiwai, Japanese golfer
Fictional characters
- Yotsuba Koiwai, titular character of the manga series Yotsuba&!
- Yoshino Koiwai, character from Masamune-kun's No Revenge series