チンポが生えたごく普通の女子高生・明日菜。
彼女は憧れの生徒会長である桜子の体操着でオナニーしているところを本人に見つかってしまう。
（もう、終わった……。私の学園生活も、オナニーライフも……）
そんな絶望に押し潰されそうになったその時、
「オナニーがそんなに好きなのだったら…… 私が手伝ってあげましょうか？」

そしてその日から、ふたりの奇妙でオナニーな関係が始まるのだった――。

___
Mostly ordinary Asuna had a unrequited crush on her classmate, Sakurako. If there was one unusual thing about her, it was that she had a penis.
Asuna was a "futanari". It was a secret she could tell no one.
She would raid her classmate's personal things. Usually she'd jack off into Sakurako's street clothes after school...... One day, Sakurako saw her.
Asuna panicked so hard that her hard-on went soft. But Sakurako's unexpected reaction changed everything.
"If you masturbate to me, I want to watch," she said.
Those words turned Asuna's flagging erection into a blasting off rocket.
From that day forward, curiosity fueled a relationship of masturbation---!