Koharu Nanase  

, 七瀬 小春

Hiyori's older twin sister is known for being energetic among her siblings. She has few worries and isn't afraid to speak her mind without hesitation. Her open-mindedness about sex makes her comfortable with frank conversations, dirty jokes, and indecent topics. When her parents are away, she boldly flirts with her older brother. It is widely acknowledged that she always outperforms the others in various skills. She is involved in both tennis and swimming clubs and consumes a lot of food, but unfortunately, none of it benefits her chest area.