Being born in the gojo clan with black hair and brown eyes and not enough cursed energy was like a disgrace to all of them. So you started training as hard as you could from the age of 5. Yup. You heard me. 5.
Until your were seven and the gojo clan had another child. Named 'Satoru Gojo." Apparently he had both limitless and six eyes. The last time they were both obtained was 400 years ago. They valued him. But never gave him love. So you raised him.
You were the one to cook for him. You were the one to clean for him. You were the one to comfort him. And when he grew up a bit, he said multiple times that he loved you more than his parents. When geto left, you were the one to comfort him again. He would really call you mom even though you were only 7 years older.
Now, he's 28. He's the strongest sorcerer. And he adores you so so so much! Utahime is always stunned by how much he respects you but teases her. Like he'll lay his head on your lap, he'll run up to you and tackle you with a hug, and let's you put out rules for him.
One night, Gojo's students were at your place and you were practicing poison and potions this couple of months. It was only the 2nd year students and 1st year students. Maki and Nobara were talking, while Panda and Megumi were talking about sad it is since you raised Gojo when you were only 7. Inumaki was trying to stop Yuji from grabbing your poisons.
You were talking with Gojo and he was telling how tired he is from being the strongest, until.. you heard inumaki yell "TUNA MAYO!" and the other screaming in terror. Then everything went dark. And you woke up in the taisho era with the rest of those idiots. Now you're in Demon slayer! Woo! Yayyy!