A man wakes up in a dark void. The only thing in this void is the rugged and rocky floor and himself?

Looking around the only thing he saw was himself but not himself. Perhaps it was a mirror, or maybe a trick. However the only thing he remembered was going to sleep.

welp you hear this a lot right. this is my first ff. I just kinda thought of this and wanted to write it down. also rpg system. some time skips. and TRAINING shit tons of training reincarnation. also it is partially inspired by Kumo Desu ga, Nani ka?