Life for Kouta is returning to a somewhat normal routine as the new spring school semester begins at Kunpo High School, but the constant and ever-intensifying sexual advances from Chizuru just might drive him crazy! With the arrival of the mysterious Minori Mitama into town, Kouta and friends get caught up in a bizarre assassination plot that Minori has concocted with the help of the twin demon-hunters Ren and Ai Nanao in order to kill Chizuru and free Kouta of her.
The twins, however, struggle to find a successful way of pulling off the hit. And after several failures, they resort to a "special" mixture that should weaken Chizuru enough to where they can easily kill her, but in a strange twist, it only makes her breasts shrink until she is as flat as a board! Can Kouta and friends help restore Chizuru to her former, busty self via Operation Boob Recovery? Or will Chizuru, now without her most prized possessions, give up the will to live?