A story about a guy who accidentally wore the pantyhose of his sister after she left it in his jogging pants. To save him from embarrassment, his friend saves his ass from the social disaster it would've been for him but it awakened a kink for both of them.
There's also a side story going on about the uke's childhood fried and his relationship with a school doctor.
My fave character is the older sister because I love how she's super caring and always looks out for his little brother.
Jackass! - Sawatte Ii tte Dare ga Itta yo?