Miki Sakashita (坂下ミキ)

Miki is Yuzuyu's cousin from her father's side. Volume Four of the manga is mostly Miki's story. Miki attended a prestigious school. She witnessed her teacher beating up a boy. When she told on her teacher everything backfired. She was harassed by her peers and teacher but refused to tell her parents. She tried to take Yuzuyu away from the Katakura residence in order to replace herself.