Mayu is a girl in junior high school who has a hot-temper and refuses to go to school. Her one and only friend she could trust in life, a ferret named Myū, dies around when she meets Kōhei and the other main characters. As soon as something bad happens, she starts yelling the ferret's name and crying uncontrollably. In order to help her grow up, Kōhei gets her mixed in with his class. Her favorite food is a teriyaki burger. She also likes things that are long like a ferret, and takes a fancy to Rumi's hair and even strange plush snakes.

From Wikipedia.