Yamitsuki Pheromone The Animation

Synopsis...

Kido is the bullied character in his class.
One thing leads to another, and he finds himself in the good graces of Hino-senpai, a beautiful girl who attracts the attention of the whole school.
Every day, the senior’s excessive skinship escalates.

After the library is closed…
A literary senior with big breasts (who likes romance novels) and a serious Yankee-like boy (who likes the senior) have a forbidden love affair in the library after school. A love affair!
What is the hidden secret of the quiet senior?