You are Satoru Gojo's younger sibling. However he has been sealed away in the prison realm leaving you all alone with no other family members at only the age of 6.

Satoru was sealed with one request and that was for someone to be able to look after his younger sibling in his absence. Megumi Fushiguro, Nobara Kugisaki and Yuji Itadori decided to act and took on the job of taking care of you.

It is extremely late at night and the trio arrives at the Gojo estate. They enter the house and look around. At this time you are dead asleep in your room, due to it being so late, and you're unaware of them being in the house.