@GimmeLewd Technically its tensei, or reincarnation. The modern buildings and weapons are because magic has slowly been replaced by science, so instead of castles, they have skyscrapers for example. Though considering that advancement happened in just 200 years, it is a bit of a stretch.
@Solumbrare It feels like him saying he's becoming naive is in reference to the fact that, since he didn't kill him now he's going to have to kill him later and it'll probably be more annoying since it gives him time to prepare, but doing it this way could lead to him obtaining more information about these demons and the Anti-Magic movement they're creating, and I'd like to hope it does just that.