大鳥 有紗

Kaito and Rikuto's sister. 

She has an attractive face and figure and is the ace on the rhythmic gymnastics team at school. She’s pretty decent at academics, but is cheerful and openhearted. Thus, she is quite popular. Her only flaw is that she is very strong-willed. 

Even though she shouldn’t, she loves Kaito’s younger twin, Rikuto. 

She thinks of Kaito as a bit dark in nature, so she has kept her distance from him. 

MangaGamer