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), Japanese voice actress
 * Kumiko Koiwai (小岩井 久美子), Japanese figure skater
 * Sakura Koiwai (小祝さくら, born 1998), Japanese golfer

Fictional characters

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