When he is invited to his girlfriend's house, which he has made up as a temporary stop, he is reunited with his former classmate Koharu (a busty beauty), who is also his girlfriend's older sister! When Koharu is not looking, she makes some sexy, provocative gestures, and as soon as her sister leaves the table, she gives him an erotic kiss full of saliva...!? Seductive sex with a cute beauty who is close to him, kisses him, and even allows him to cum inside her!