Chizu was relatively calm and somewhat quiet, yet she felt particularly disgusted by the narrow-mindedness of her male classmates. Her chair was black, fancy, and meticulously designed, with an elegant shape that suggested it was very old.
While at school, Chizu was in love with her teacher, but she was being deceived. He lured her into a date and then blackmailed her, leading to her being gang-raped by his friends. This traumatic experience caused her to carry a knife with her at all times. After killing Kako Isao, she completed his battle. During the combat, she revealed she was pregnant and used Zearth's power to kill all the men who had assaulted her, except for the teacher. Her older sister, who was also in love with him, stopped her from doing so. Following her death, the other children discovered that Chizu's baby (who died with her) was also listed in the contract. This revelation indicated that one of them, besides Kana Ushiro, was not bound to it.
Similar to Kako's story, Chizu's scenario underwent many changes in the anime version. She was seduced by her teacher just like in the manga, but instead of being blackmailed, he sold some pictures of them having sex, which ended up on the internet. Despite the faces being digitally altered, they were identified by her classmates, leading to the teacher being punished by the school's principal. He begged for Chizu's forgiveness, and just after she accepted his apologies, she found out he was also dating her older sister. After Kako's death, she was chosen to take his place. Just like in the manga, Chizu tried to kill her teacher using Zearth but was stopped by her sister. The rest of the children only discovered about her pregnancy and the fact that one of them was not bound to the contract after her death, when Moji witnessed two slits blackening out from Zearth's face, representing her and her baby.
(Source: Wikipedia)
