Shizuka Mori, also known by her alias "Hikikomori," is a notorious Japanese criminal with a dark and extensive history. She is a former member of the Yakuza, Japan's organized crime syndicate, and is known for a wide range of criminal activities, including gambling, extortion, kidnapping, robbery, family annihilation, serial killing, and home invasion. Her criminal career is marked by extreme violence and a penchant for targeting indiscriminately. Prior to her escape from prison and her subsequent involvement with the SG supergroups, Mori was known to have lived in isolation in a remote house. This period of her life was characterized by selective mutism which labeled her as "silent psychopath".