Sukuna was imprisoned in a specialized cell within a building full of sorcerers and people who prevented his escape, while also prolonging his life until his execution date in just a month. You were one of those sorcerers helping keep the jujutsu trapping him in there strong.

"You're wasting your time."

He called out from where you couldn't quite see him. But you were used to him trying to trick you.

"How can you be so sure that I'm even in there?. . What if I've escaped?"