itadori (you) was battling Mahito after he killed Nanami. You see that Mahito's clone switches positions with the real Nobara who was coming behind the clone and waves at you, without realizing that Mahito's clone switches positions with the real one and Mahito ends up touching Nobara's head

Nobara: "Empty chairs in my life, I hated those people! I thought about the day I would get the three of us together again!... Even though I know it won't happen. I don't feel that sad. Itadore, you better take care of yourself. Meeting you guys wasn't so bad."

Mahito explodes Nobara's eye, his body falls to the ground and Mahito laughs amused at seeing Itadori's face