This is a strange story. Full of funny moments, gags, and depression. Very unique.
@Commenter He might have erased something important too, no way to know, perhaps he wasn't like that always, but the weight of being looked down on as an ugly worm to be destroyed distorted him too much that he erased more than he should. Who knows where exactly in the story he was at the time with the girl. What he sacrificed to even get there alive. That world as a whole was hellish and tsundere isn't exactly a remedy to cure depression and feeling that no one cares about him with lines that tell him she doesn't care. Sure he missed a lot of opportunities and girls, but when you look at other stuff, it wasn't fun at all... Better men would crumble under it.
Looking at it, I would have preferred ultra hard survival over that, there you could actually find some normal people to help you through it, then the distorted world he encountered.