Chika Midarezaki

Formerly known as Senko Himemiya Himemiya Senko she is Ykas biological sister and is the last one to join the Midarezaki family. She was the former Solitary Doll before Yka was born. After Yka became the next Solitary Doll she tortured her in various ways and even gave money to her classmates to bully her. However she remembered the promise with Ginichi Kizakura now Ginka Midarezaki and regrets her wrongdoings. She actually doesnt have Enkas DNA but she becomes a member of Peaceful Family Operation by Kykas ability.