Koishi
Koishi is a Japanese surname. Notable people with the surname include:
- Hirotaka Koishi, Japanese baseball player
- Kiyoshi Koishi, Japanese photographer
- Tatsuomi Koishi, Japanese footballer
- Tetsuya Koishi, Japanese footballer
- Yūma Koishi, Japanese cyclist
- Koishi Komeiji, a character in Subterranean Animism from the Touhou Project series