[quote=@LupusIntus]
<Snipped quote by Lugubrious>

Of course our wonderful OP can answer, but I will point out that Umbra Rose's primary purpose seems to be protecting monsters from human hunters so an 'infitrator' would take on a more nefarious tone in context.
[/quote]

That's definitely part of it. This character is someone who, in turn, investigations supernatural phenomena in order to keep humanity safe from outside threats. Wherever there's a veil, someone's bound to pierce it. While he's staying undercover, though, he doesn't go in with any preconceived notions or intentions other than to learn, so he wouldn't be a threat necessarily. Just kind of a weirdo.