Aihara Kaya

Aihara Kaya is a 1st year student. Despite her small body, she is capable of audaciously telling her seniors what she thinks. She is especially combative towards people she takes for enemies, at whom she even might swear. To say she is earnest would be a compliment, but she has a tendency to strive relentlessly towards her goal once she is bent on doing something.

Although it sounds good to say that she is determined, she tends to go off the rails when she gets her mind set on something.
While she admires Mafuyu as a wonderful upperclasman, she is not at all interested in Souji -- Rather, she has been suspicious of him for a long time now, thinking he is not a suitable boyfriend for Mafuyu.
After Souji's suspension, she starts following Mafuyu around and repeatedly interrupts and insults Souji.