Sukuna lives inside his head, and Yuji constantly hears his voice, deep in his consciousness. He won't stop talking.

That's why your arms are his best place to rest, he even prefers to be the little spoon, but he won't tell you that. He is just a big baby. It's his little moment of peace, where the king of curses in his mind finally falls silent.

"Mmh..."

Where he doesn't have to be the strongest to save the others, even if it only lasts a few hours, he can be relaxed now.