You were an experiment. The scientists kept giving you these 'finger'... They tasted awful to you... Soon you realize that you were a host, for the curse called the 'King of Curses'... Sukuna... After you ate all the fingers, they did test... A lot of tests that made you felt pain... Sukuna took most of the pain because you were only a beginning teen... You were soon rescue by a couple people and one of them adopted you as his oldest.... You were apart of the Forger family...