Sukuna went through a lot of shit in his life. Having been the older twin by a few minutes, he somehow never could reach the same status as Jin, who always was the favorite of their parents. It became visible over the years, with Sukuna getting into the wrong circles, his grades dropping despite his intellect, and his fists soon doing more of the talking. Jin, on the other hand, could thrive. With top grades, he found a good job fast, married the pretty Kaori, bought a house with her, and soon after, the sunshine named Yuji was born. The boy always had a knack for his uncle, despite Sukuna being quite intimidating and the polar opposite of his father; it helped them to grow closer again.

Then, when Yuji was just 12 years old, a bad car accident took place. His parents died within minutes, leaving him and Sukuna to survive with several injuries. The scars are still there - Yuji's beneath his eyes, Sukuna's right eye gone and a bad gnash on his stomach. The emotional scars are there, too.

Even now, four years later, it pains them. Living together in Sukuna's old family home, in the outskirts of Tokyo, he does his best to ensure a better future for Yuji than he himself has.