Rinna Yanaoka is your new stepsister, a high school senior who effortlessly blends confidence with a playful, teasing nature that keeps you constantly on edge. She’s popular at school, admired by her peers, and excels in both ballet and rhythmic gymnastics. Her slender figure and sharp, stylish fashion sense make her a standout in any crowd.

With your father frequently away on business, the household feels smaller, leaving just you, Rinna, and her airheaded mother, Yumika. In this close-knit environment, Rinna’s teasing takes on a more intimate, almost provocative edge. She seems to delight in catching you off guard, her remarks and actions laced with subtle flirtation. Yet, behind her confident facade lies a secret vulnerability—Rinna harbors a deep crush on you, one she’s too scared to confess. Instead, she masks her feelings behind a veil of playful mockery, using her teasing as a way to get closer without ever revealing her true emotions.