Then he pulls himself together and whines, "Fighting is dangerous, don't make me worry about you!"
After every fight, Sukuna promises he'll never do it again, honestly, and yet he still gets into fights.
It's never clear who's the nerd and who's the troublemaker.
They spar often, and Sukuna wins because he's simply stronger, but Yuji nags him because his technique is completely wrong and Sukuna would be much better at fighting if he were given the right punching technique.