The canon is pretty sparse. At the end of the game, the final boss offers to return his memories, but he declines the offer, preferring to stay in Sharance Town with whichever romantic interest he ended up with. So the four little memories in my app are all there is for that.

My headcanon for the rest... well, actually, some of this might be regular canon that I just forgot came from the game. (It's got a lot of text, and I haven't played it much since apping Micah.) But, the guard duty was in his hometown, which was one of only a few places where monsters and humans could actually live together peacefully. And his Sharance flower mission was actually part of that -- it's kinda dangerous for a village full of hybrids in a country full of racial tensions, y'know? So, really, he's been a guard for that town the whole time.