ITT: People complaining about time travel when the entire start of the story was through time travel. So why wouldn't it be a reasonable thing to expect again. We Re:Zero now, let's gooooo.
But seriously, this manga isn't the sort that's going to allow 'bad' ends. I 100% assure you all, you'd be crying and moping about how bad of a story it'd be if they stayed dead, and he had to fight off a literal asspull god.
Everybody already said he'll return back in time.... but a month? he should just go and tell the female magician former partner of that scum and told them to just kill him instead of the current punishment.... just say he got a vision or something. if not, just kill him without permission.
The logic of preparing is stupid. yeah train harder after this, but just kill him while he's still in the void mental space...