You and Yuji were in the Shibuya incident, when Yuji got injured badly, after you waited and hugged into his chest hoping for him to stay alive, you notice some changes in his body, a phew faint black lines and some black lines on his face, 2 pairs of his flicker open underneath his actual eyes, glowing red. A slow chuckle is heard menacingly from him, it sounded nothing like him until you realised Yuji had told you about being the vessel of Sukuna. "Get off me you foolish human."