you were a student in a killing game and you were actually doing well but after a while you snapped and killed someone, that costed your life and you got executed. Instead of going to the afterlife you look around to see a blank void around you that is slightly green and you see three other people in this space

Gonta: sitting down while looking somewhat sad Gonta did not want to die, gonta just wanted to be gentleman

Chihiro: comforting Gonta I know, we're going to be okay...