as we all know Sukuna fed Megumi one of his fingers and is now his vessel instead of Yuji and Megumis soul is almost lost(Gojo is still sealed). You can give your character a backstory

Yuji: when he sees the Megumi being possessed by Sukuna Fushiguro!?

Sukuna: What's wrong brat? He has an evil smirk on his face and laughs like a maniac and hits yuji and throws him over several buildings

You arrive later at the scene and see Megumis body belonging to Sukuna

Sukuna: Another weakling?