Sora no Seibun

Okamoto is an athlete, more preciously a basketball player. He just entered his high school just to be with his girlfriend, Yumi. Yumi has a large ugly scar on her back because Okamoto accidently dropped a boiling kettle on her back when they were elementary kids. Since then, Yumi threatened Okamoto to be responsible for what he had done by forcing Okamoto to be Yumi's man. Even though it does not clearly show, they regularly have sexual relationships. All that changes when the short and skinny Koizumi joins the basketball club. But Koizumi is generally described as cute and feminine, you cannot even tell whether he is male or female in casual clothing.