Tonari no Futomomo-san

Kuonji is a perfectly healthy high school boy, but his heart is held captive by one thing: the thighs of the girl sitting right next to him! Following a chance accident, he finally makes contact with the girl who was supposed to be way out of his league. Now, Kuonji's dull everyday life is about to take a massive turn...!!?

(Source: MangaDex)