Hikari, a young tutor with a perfect body. Her large breasts make Hiroshi unable to focus on studying. Knowing that her student is infatuated with her breasts, Hikari helps satisfy his sexual desires so that Hiroshi can focus on studying. However, the student cannot have sex, so Hikari helps him by giving him a blowjob. Hiroshi's father accidentally discovers everything. He intends to have a serious talk with her, but Hikari seduces him instead. His wife has been gone for a long time, so being seduced by a beautiful young girl like her makes him unable to resist. Not only seducing the father, Hikari even seduces Hiroshi's brother, and finally takes Hiroshi's virginity. Since Hikari had sex with the whole family, Hiroshi's grades improved, his brother worked harder, and the father finally enjoyed the pleasure he had been missing for so long...