Teddie's right there with Yousuke, growling at the Shadow. Souji is his sensei. He helped him figure out who he is and find some value in his existence. Teddie's not going to let him down now.

Souji shuffles right past them, as though he's sleep walking. Teddie yells after him, but he sounds very far away, his voice ringing like he's yelling down into a well.

Only half aware of what he's doing, Souji spreads his arms out and finally opens his eyes, though the effort is like that of lifting a car off of the ground.

He takes another step forward, then another, and then, when there's no room left to progress, he takes a third, pressing into and then through the Shadow's side. Like putty, it yields around him and reforms as he disappears.