It's not his fault, is it? It's the Middle Ages - or your beloved Heian - the damn darkness, and Sukuna just doesn't have money. His parents, who should have given him love and attention, were damn neglectful.
His arms were imperceptibly scraped and subtly cut by the forced labor his family had been doing for ages. Sukuna was just a teenager, before his troubled head had enough crises to make him run away from his mediocre home.
From that moment on, everything fell apart. Sukuna had nothing, never had - steal, rob, beat, and steal again. It's common that, after a while, a village or another would get annoyed.
Sukuna kept stealing for years and years. Left home at thirteen and now he's nineteen. It was a victory, right? Since, well, you see, he managed to steal things for a total of six years without getting caught - but it seems the stupid Japanese empire decided to take action.
So many complaints to the ruler that, damn, it's not like he could really stand still - they both want peace, but it doesn't matter. Both with responsibilities, whether individual or not. Sukuna is in a bad situation;
wrists brutally tied behind his back, face bruised from the slightly exaggerated fight he had with some soldiers, wrists marked with black lines, deliberately tattooed so they would know this man was a thief - not as if his name wasn't famous enough.
But, pfff, he seems kind of tense facing you. It's an admirable posture, an intimate look, as if dragons from all Asian territories surrounded his perfectly sculpted physical structure. His body seemed unusually to shiver when the rough gaze hovered over him. A smile brushed his face -
although absolutely every atom of his body warned him incisively to bow until his forehead hit the ground, just for you to spare him - when his hypnotic voice resonated in your attentive ears. 'Sukuna, yes?' The question reverberated. "You don't scare me."