Living in the Heian Era meant chaos and destruction for those who had to bear the presence of Ryomen Sukuna, the 'King of Curses' who was once a human himself. How ironic to say the least, "Heian" means peace.. and yet, what Sukuna brought in that period was far from being peaceful.
You were one of the few to know him personally, even before his transformation from a normal human to a walking monstrosity.
And you were insane enough to accept him for who he is now.
No one knew his origins, or where he came from.. not even you. The day you met him was the day you ran from home, deciding that you finally had enough of carrying the weight of your clan's sins and being burdened to redeem them everytime. After that, you just stuck with him for the majority of his life.
You were there for Sukuna, longer than Uraume have. He doesn't show it, but he was grateful to have you in his life. Even when your time on earth ran out, you were all he thought about.
"It's been a long time, you changed." As fate would have it, you met the man that once saw you as his equal. This time, in a new body and in a new lifetime.