First introduced as the 11-year-old heiress to the Anastasia Ruby, Chiko lived with her aunt and uncle after her parents died. However, she acted coldly towards her relatives because she knew they were slowly poisoning her in order to inherit her parents’ fortune. Luckily, she was saved by Nijū-Mensō, who gave her the choice to leave with him, when he had coincidently been there to steal the Anastasia Ruby. She admires Nijū-Mensō a great deal, and he becomes a very important role model for her. Chiko learns many tricks from everyone on the team, and has the making to become a great thief. She usually only performs minor roles during the jobs, such as distraction roles. One of her aliases is Lilly, the high rope walker. At the age of thirteen, Chiko appears to be the last survivor of the Phantom Thief team, but that gets called into question when a detective who calls himself Akechi visits Chiko's house. After hearing that Nijū-Mensō may still be alive, Chiko vows to find him by becoming a detective herself.