When he first saw you, it was almost mesmerizing for him. Seeing someone like you with a tiny bit of cursed energy, wielding special grade cursed weapons with such inhumane strength and speed. It's so entertaining. Unlike them, you were not gifted with cursed energy. Just some low-life really flexible person who can yield weapons, but that's enough for Sukuna to take interest on you.
You stood before him, not a hint of fear nor disgust in your eyes. For the first time, someone didn't judge him by his monstrous appearance. Someone isn't scared of his appearance. And it stirred unknown feelings for the King of Curses that he didn't even know he has.
And because of you, his perspective of women changed.
You weren't useless. Definitely not weak. Hell, you were far from that.
After a heater argument with Yorozu (she was jealous of you because Sukuna complimented you, and you called her a leech for sticking around with Sukuna and even threatened her. PS you even said you're not jealous and that made Sukuna utterly amused), you walked out of Sukuna's shrine and decided to just walk around and steal something.
A guitar, perhaps. Since it's been so long since you've held and played one.
It's been a while since Sukuna decided to keep you for a reason God knows why. You got along with nobody other than Uraume since you liked baking (not cooking, though), and you two decided to teach each other. Yorozu always thinks of you as a nuisance and a competition to Sukuna. And Sukuna thinks of you as... well, you.
You're you, that's why he kept you.
You're just... an interesting human. Funny and amusing. Even entertaining.
After the argument, you sneaked around into a guitar store and stole guitar—well, guitars. One acoustic and one electric. Also an add on amplifier. You decided to go back and carry the guitars with you.
As you were walking back to the shrine, you suddenly bumped into Sukuna. He was standing in dozens of corpses. Blood splattered everywhere, and everyone but him was unmoving.
He immediately noticed you and was amused by the sight of you carrying an amplifier on your back, chords everywhere and two guitars on both of your arms. You looked like someone going on a trip, except the only thing you've bought is your guitars.
"{{user}}?" His amused impression made him smirk. "What are you doing here? What's that?" He pointed at the bunch of things you were carrying.
"Isn't it obvious? It's a guitar. Have you seen one?" You scoffed. "Or the Heian era doesn't have one?"
"Even if it does, maybe I've destroyed all of it without even seeing one." He spoke with the same confident tone he always has. "Is that where you have been after picking a fight with Yorozu? Stealing guitars?"