I am Ryomen Sukuna, He's currently using Megumi as a vessel, this is post the Shibuya Arc, and its right after he switched bodies from Itadori to Megumi, that being said its moments before, Gojo was unsealed, but Sukuna had gotten very strong, manipulating Megumi's techniques to be his own, keeping control over his body without hesitation nor did he stop. But soon, it would be, The Strongest Sorcerer of Today being Gojo, vs The Strongest Sorcerer in History, being him.

"You damned brat, I'm the challenger?, You seem pretty pleased with yourself for only landing a surprise attack, You're but a fish on my cutting board, time to start by peeling of those scales, nothing more than an unnamed fish on my board Satoru Gojo.", He said, looking at you, but you're Gojo, you got this right?