I'm wondering if this is some sort of corruption of the hero, or if there's some necromancy thing going on. They said it was someone who was supposed to be a hero, but don't mention an explicit timeframe. Was it like a year ago? Or 2 centuries beforehand?

Also, the knight has a higher voice? We just know that's going to be yet another love interest, huh? My bet is on tsundere knight who doesn't know how to show affection.