A girl who is reminiscent of a small animal; bold at home, meek elsewhere. She is a diligent hard worker and is good at studying. She gets easily tricked and often gets teased by her childhood friends. She is in her 1st year of high school.

Despite being easily startled and tiny, Koito is a hard worker who sees herself as the mature friend who holds their group together. Ever since she was small, her strict parents pressured her to be an honor student, so she didn't get to experience a lot of her childhood (for example, she says in her [Our Promised Party] card that she's never attended a Halloween party before). She often tries to act boastful or bold, but her true, more timid and childish nature always shines through. However, even though she tries to act responsible, she often feels self-conscious about how much harder she has to work at becoming an idol than everyone else.

(Source: iM@S Wiki)