I remember reading a hentai but I can't remember the name. But I remember how it goes.

A girl stopped growing when she was young. So she's 20 or so but looks like she's a child.
The story begins with he having sex with her bf outside and her using her panties and hair to get him on.
Later the police sees them and he gets pissed at the guy for screwing a child( cause he thought she was a child) but then she throws her ID card and reveals that she is an adult. She also has 2 sisters and a mom and the bf has sex with them later.
According to this person the girl's name is miyuyu and called yuyu. and yuyu and bf was seperated when they were children (although i don't remember this). He also says that it was a mini series or sth(again not sure if it's true).

I've posted several times on /r/ and /b/ but got no answers.
Please. Please help.
Pic unrelated