Koiwai
# Koiwai

Koiwai (written: 小岩井 lit "small rock well") is a Japanese surname. Notable people with the surname include:

* Eichi Karl Koiwai (1920–2009), American judoka
* Kotori Koiwai (小岩井 ことり, born 1990), Japanese voice actress
* Kumiko Koiwai (小岩井 久美子, born 1975), Japanese figure skater

## Fictional characters

* Yotsuba Koiwai (小岩井 四葉), titular character of the manga series Yotsuba&!
