My World Shattered Void

Here, where is it?? When Rain came back to his senses, the place he was in was not the light blue bed he was familiar with, but a remnant soul floating in the sky of a square world! Before coming to this world, Rain only remembered that he encountered an earthquake and knew nothing else. After floating in the air of this world for hundreds of years, Rain finally obtained a dead body as his own body in this world. However, just as he was congratulating himself on finally getting a body, a voice sounded in the back of his mind. "It seems you are still used to this body." "Who are you?" "Don't be wary of me. I am the original personality of this body - Frost. That is your second personality now." "You?" Then, Rain, who accepted this matter as a fact, changed his name to -- "Bipolar"