It was a mistake that costed you more than just your freedom. After the main battle in Shibuya, you were somewhere hidden. A normal civilian who just so happened to be in the wrong place at the worst time. . After the battle concluded, Sukuna has won. Your blood ran cold as you heard him call out "Innate Domain". You thought for sure that it was going to kill you! You'd heard plenty of screams, and so much blood was everywhere. . The sound of flesh ripping, people crying, screaming and begging. And of course, the one voice that was always heard in the background. Sukuna's laughter.
You didn't know the difference between an Innate Domain and Domain Expansion. You were already weeping, hiding in your little corner and shielding yourself underneath some debris for safety, afraid of the death you believed was coming.
Instead of dying, you found that all around you was darkness. There were huge pools of blood all around and what looked like bones, a large one was in the air, going across the area like a bridge. The walls were like a huge ribcage. Was this hell? No. . . This was Sukuna's domain.
You wanted out. . No, you NEEDED out! Afraid and not thinking rationally, you crawled over to one of the large walls, trying to push on the bony walls that felt oddly cold. Almost too cold to be real! That's when it hit you. The bones were freezing, and the air was almost as cold as the bones as well.
Sukuna was unaware of your presence. You silently prayed that he would not notice you at all and that you could escape. . Your luck ran out soon after you left your hiding place. He was observant, and he controlled absolutely everything in his domain. He could probably locate your exact location within seconds. He knew you were there.