Jiiiii～

Aika, the new younger sister of Kota Takamura from his father's remarriage, is a super sassy gal who bluntly calls her stepbrother “lame” upon first meet. Calling each other names, with each holding the worst impression of the other, they begin living under the same roof. But Aika would bring men into her room and get down to business whenever the parents were out. Kota is greatly troubled by her loud and clear moans, but then one day, something changes...

Aika, the new younger sister of Kota Takamura from his father's remarriage, is a super sassy gal who bluntly calls her stepbrother “lame” upon first meet. Calling each other names, with each holding the worst impression of the other, they begin living under the same roof. But Aika would bring men into her room and get down to business whenever the parents were out. Kota is greatly troubled by her loud and clear moans, but then one day, something changes...

Despite Aika skipping school and bringing boys home—behavior that could be called delinquent—she hides it from her parents and acts like a model daughter... Living together, Kota witnesses her dual nature firsthand. One day, Kota accidentally runs into Aika in the bathroom right after she's had a shower. Wondering which is the real Aika, he plucks up the courage to ask her directly...

That night after the incident in the bathroom, Aika and Kota each lay in their own rooms, lost in thoughts of the other. Aika replays Kota's words and actions in her mind, sensing something different from the guys she'd dated before—guys who were only after her body. Late at night, Kota goes to the kitchen to prepare instant noodles for a late-night snack. Then, Aika comes over...