鈴屋 美菜子

Hiroki's younger twin sister. She is a new student like he is and so she doesn't have any friends yet. She calls her brother a pathetic pervert and refuses to acknowledge him at school and even goes so far as pretending she doesn't know him. As his popularity grows with the White Lily Society however Minako begins to grow jealous of his popularity and she even tries to join the club but Izumi refuses thinking she'll just be a nuisance.

Hiroki defends her however hoping to set her 'flag' as a heroine because he feels it's his only chance to commit incest. Besides, his sister is very cute. After he tells her his plan of making his own harem she agrees to help him.