Locker Shoujo Nanami-chan [English], by Sugiura Sen
Biribiri, Zebon20 and PureEnergy bring us a funny uncomplicated share, thank you very much
We start with a highschool girl masturbating in a locker while peeping on her classmate having sex. Turns out that was anal sex, and the classmate knew and was putting up a show. Naturally, she is going to introduce our female MC to anal sex with her sexfriend.
Take it or leave it, as you like, me, I enjoyed it ^^