HOTERU WATASHI NI KOI WO OSHIETE

Hoteru Watashi ni Koi wo Oshiete summary:

Miku is a high school student who is very good at fantasizing, but knows nothing about real boys. At school, she hides her interest and acts as a pure character, but one day her childhood friend, Shida, finds out that she's been reading erotic manga!
"I thought my life was over...but then Shida-kun asks me if I want to gain some experience with guy...?"
It's a romantic comedy about a girl with a delusional brain and a teasing boy in a public bathhouse.