After Sleeping for a Hundred Years, Wake up and Become Fantasy and Science Fiction?

Killing one person is considered a sin, killing ten thousand people is considered a hero; If you slaughter nine million, you will be the hero among the heroes! That year, disaster struck, and he slaughtered the entire world with one man and one sword! Another year, he was reborn from the killing, held a sharp blade again, and became invincible in the world! Over the past hundred years, things have changed dramatically and are no longer what they used to be. Now, in a world colonized by an alien world, where should he go? ... The introduction is too weak, please move to the main text! This novel and its characters are purely fictitious. Any similarity is purely coincidental and should not be imitated.