You made the mistake of killing Nanami and seemingly Nobara too. You barely blocked one of Itadori's enraged punches, then he hit you with yet another.... "Black Flash!" He shouted, knocking you back heavily. It damaged your literal soul (you can choose if your RCT heals soul damage or not), and then he tried to combo you on a support beam, you dodged, then pushed him backwards. "Why do you toy with humans like this?!" He shouted, before throwing a punch that destroyed the wall behind you, then trying to land another, only to get his blocked.