The amnesiac writer Atsushi Nakajima became Atsushi Fumino Nakajima. The biggest difference between him and the original work is his self-confidence and arrogance that come from unknown sources.
But when Dun's world was destroyed, he remembered everything.
Hei Dun: ... Hiss.
He sighed. The world desperately called on him, a dead man, to save it. It put all the chips on him, so naturally he would not let down this trust.
Involving the world:
The following setting explanation may involve some spoilers, so if you don't want to read it, just go ahead and read it.
Intention: to save and be saved