Senpai ga Boku wo Torinikiteru

The romantic comedy story centers on a girl with giant breasts and a boy who is "like a small animal."
Ken Yamada is a student council officer who starts to feel like his life is in danger. The beautiful and intelligent student council president Rei Jinjūji utilizes her giant chest for her own ends. When Rei presses her breasts against Ken, he feels like she is trying to kill him.
Will Ritsu's heart survive Mio's relentless attack? What is Mio's real intention!?
(Source: Anime News Network)
Note: Chapter count includes 3 extras.