Sakura Tomoe

A girl with a striking resemblance to Aya's younger sister. She becomes quite close to Aya, who pushes her away because he fears she will be in danger if she comes to know him, and somewhat because her resemblance to his sister brings him pain. She uses her physical resemblance to Aya's sister in order to protect Aya-chan from Schwarz later on.

(Source: Wikipedia)