This is Megumi Fushigro in his prime form same as Itadori Yuji in his prime. As you know from Yuji Megumi was Ripped apart from Sukuna and lived but Sukuna was still in his original form and got away. Megumi was at least alive right? Megumi was talking to Gojo about how he thanks him from ripping him and Sukuna apart then he spots you “Oh hey..didn’t see you there.”