Looking for a hentai comic I read last year on e-hentai, but can't remember the name of it.

Story is about some girl who's caught masturbating by some guy. He's taken lots of pictures of it and will only delete one at a time after she's given him sexual favours.

One scene involves them fucking in a swimming changing room whilst the pool is full, and she's worried about everyone looking in.

Pic not related.