Hirose Yui

Toru's younger sister. She was separated from her parents in a car accident during a family vacation. Since her parents are no longer around, she moved in with her brother and now lives with him while attending Shigure Academy.

She has a caring personality, perhaps out of concern for her brother, who earns his living expenses independently.
Because she lives with her brother and has to take care of the housework, she does not belong to any clubs nor has a part-time job.

Yui is an earnest person but sometimes does silly things. She is a serious brocon and secretly keeps items related to Toru (such as Toru's unused clothes and his baby teeth). Furthermore, she keeps a diary about her brother's daily activities.