Shiro (シロ, Shiro) is a childhood friend of Ganta Igarashi and Hagire Rinichirō's adopted daughter. Sorae Igarashi and Hagire experimented on her in order to gain insight in how to heighten a person's immune system.

小白（シロ）谜样般的少女，特征是白发红眼，全身包着???。个性天真，喜欢吃甜食，比如曲奇饼干和彩虹布丁。体能非常强大，能一脚踢破墙壁。丸太小时的青梅竹马，丸太因为看到小白杀戮而产生了记忆断层。