Yuji ate Sukuna’s finger, he accepted easily that he’d have to join Jujutsu High now. Yuji did feel happy about it though because Megumi was gonna be in his class, the boy that was there during the fight he had with a cursed spirit at his old middle school in order to save his friends. On top of this, Yuji has been with Gojo for a week now, only because he had to wait until the school year actually started. Gojo kept an eye on Yuji to observe how Yuji did as Sukuna’s vessel, he found it amusing that Yuji could go on with a casual life while hosting the King Of Curses.
Yuji's rapid improvement is not unnoticeable. Yuji has learned several cursed techniques, adapted easily to fighting special grade curses after only 4-5 months of training. The grow rate did not go unnoticed by no sorcerer, especially Higher Ups, Gojo, Todo, and Nanami. Todo is proud of Yuji, Higher Ups hate this a lot, Nanami keeps pushing Yuji to get even better, but Gojo... He started getting concerned about something... so he decided to dig into Yuji's family history for the reasoning of how Yuji could be rapidly improving. Sukuna already knew the answer, he knew why Yuji is improving so much, he knew for a long time, he just never cared enough to say it.
Gojo: "Hey Yuji! Let's go for a walk!"
He said to Yuji with a fake smile, Gojo needs to pull Yuji away for a moment to talk about something so important. He knows he needs to tell Yuji about why he's improving too fast... cause Gojo's Six Eyes have provided Gojo the information that Yuji is related to Sukuna.
Yuji: "Okay, sensei!"
Yuji says with a smile and started following Gojo. Gojo picked up Nanami too, Nanami joined since the topic is important, and Nanami should talk to Yuji about it too.
Sukuna---who's inside Yuji---picked up quickly about what Gojo and Nanami are doing... he didn't know that it's to tell Yuji the truth, he just knew they're trying to pull Yuji aside. He narrowed his eyes, aloof expression stayed on his face, as he sits back on his throne of bull skulls inside Yuji's mind.