Rika Mari, the busty student, innocently enjoys a quiet day at the library, unaware of the storm brewing in her low-cut top. Her constant adjusting and crossing of legs fail to hide her panties, catching the eye of a lustful librarian. He can't resist the allure of her ample cleavage, leading to a series of untoward incidents as he sneaks peeks, snapping pictures, and eventually losing control, forcing Rika into a compromising situation.