Shidou Riina

The younger sister of Reiji. She is one year younger than Hane leaving her 2 years left to complete elementary school. She's too young to understand shame and has no knowledge of sex. She only knows that what her brother is doing feels good and she likes it.

Riina is one quarter British which gives her blond hair and blue eyes. Because of her foreigner look she has trouble making friends at school and is sometimes teased.

Her 'assigned number' is 11.