The super erotic production group Ifi-Wo-Ka has animated the popular CG collection of the doujin circle Yorokobi no Kuni! rnWhen you go to a group party invited by a friend, you'll find your own younger sister, Mina, there! The two decide to participate while hiding the fact that they are brother and sister, but the king's game begins, and the punishment game is full of naughty things! Show your breasts, show your panties, play Pocky games, and even show your masturbation! Mina, who was covered in semen by her own brother, couldn't refuse her brother's penis...! ? rnrn★SynopsisrnWhen you go to a group party invited by a friend, you'll find your own younger sister Mina there! Two people who want to improve the atmosphere at a group date