I might sound insensitive but his mother ain't gonna come back even if he went back so yeah -.-
That's not the point. Kouichi's mother died BECAUSE of Kouichi, which is exactly why he's so adamant about living a life that she can be proud of; if he doesn't go back and make a life for himself in his own world where she died, it means her death was in vain. It's not about bringing her back, it's about making up for a death that he feels was his fault in the first place.
Is it just me or does Hamin looks like Hyunjin from SKZ (Stray Kids) ? (≧∀≦)