Tsutsukakushi Tsukiko♀

The main heroine of the series and a first-year student. She shows her emotions easily and goes to the Stony Cat statue where she wishes to become more mature and less open with her emotions. The Stony Cat statue takes her words literally, and as a result, she has become unable to express any emotions on her face, regardless of the situation. She is often compared to a cat by Youto, and has a tendency to bite him when she gets angry. Tsukiko lives together with her older sister because their parents died when they were younger, but has a bad and distant relationship with her.

[Edited from Wikipedia]