Shota comes to hang out with his classmate Kunio, hoping to see his cute big-breasted sister. His friends are wary of the sudden visit of the precocious, perverted Shota, but they're no match for the cunning Shota, and his precious big-breasted sister plays all sorts of naughty pranks on them. In the confusion, he gives him a handjob and blowjob in the bathroom, pranks him and fucks him as things go, and has incestuous sex with his big-breasted, lewd sister...