Yuka Arai is a beautiful, kind, and highly popular announcer. However, in front of her younger brother, she's a mean big sister who bosses him around! Big sister Yuka teases her brother by showing off her sex life: giving his friend a ball-licking blowjob until he cums, making him film a sex report, having bath sex while letting him peek, and even having a threesome that leaves him out. Despite him confessing his love and even taking her virginity, she continues to act in ways that make him jealous. Will the sister-complex brother ever be able to unite with his beloved big sister...?