The mischievous gyaru little sister "Rika" has become a schoolgirl who grows increasingly curious about sex. To seduce her older brother—you—she begins learning dirty talk and flirtatious phrases. Whenever she finds you anywhere in the house, she boldly approaches with provocative words. She sneaks into the bathroom, slips into your bedroom, or invites you into her room, teasing you in lewd poses that captivate your gaze. With taunting lines like "Onii-chan… wanting to make a baby with your little sister? You're such a total pervert, lol ♪" mixed with gyaru slang, her interest in sex deepens more and more. Her passionate behavior makes it seem as though she harbors special feelings for you alone. Seduced by her relentless advances, you'll find yourself completely drawn in, eager to share intimate moments with her.