Mika, also known as "Mikan" (みかん), is a shy and clumsy girl who is constantly falling down and bumping into things. As an only child, she has taken advantage of her position and has been spoiled by her parents. After meeting Manami, Mika becomes very attached to her. At first she was the only member in the student council, taking the position of secretary, but was later joined by Manami when she became the student council president.

At first she is unsure about Manami's strange enthusiasm and is unsure how to work with her within the council. As time passes, Mika begins to become more enthused herself by going along with Manami's plans to reform student life at Seioh. Mika seems to be the least mature of the five main characters, even going as far as to believe "little people" finished the work for the school festival promotional video while she, Minami and Mutsuki were sleeping.