Hagiwara Michiru

The protagonist's blood related little sister.
Being an honorary student, she got enrolled in Kitahana Private All-girls School. Since it is close to where her brother lives, she moved in to live with him.
She is not good at expressing her thoughts and feelings, and even less so in front of those she does not know well.
Due to her introvertedness, she is quite a foul-mouthed person.