She is an assassin from "Orchestra", an international team of assassins which at one point had eight members. Shisho and Chinatsu are the last surviving members.
It is revealed that she came from a well-off family, until one day when she and her family were attending a play in an opera house, Orchestra barges in to not only kill their intended target but also mercilessly massacred all audience members. Chinatsu is the only one who survived. Though she does try to avenge the murder of her family, she only manages to wound Shisho. Shisho doesn't kill her, instead, he abducts her and trains her to be his protégé in which she developed Stockholm Syndrome and she becomes as proficient and ruthless as Shisho.
She is killed by Koko's team, soon after Shisho is killed in front of her.
