Is your character any manner of spirit, youkai, demon, or otherwise inhuman being? Does your character share their body with any manner of spirit, youkai, demon, Persona, etc?
Yes, Charlie is a vampire. While he does a good job acting human, he's cold to the touch, has yellow eyes, and anyone with the ability to sense the supernatural would notice that he's inhuman.

In his canon, there's a concept of "the beast" which is the vampyric blood itself. Some regard it as a separate entity from the individual, while others interpret it as a manifestation of the individual's worst nature. I like to leave it vague, so totally up to you if Matoba senses an instinct other than Charlie's.

Are you okay with Matoba sensing your character's inhumanness/their ability to see/their magical or spiritual artifact?
Yes absolutely go for it \o/

Are you okay with Matoba testing your character's inhumanness/their ability to see in minor ways (such as asking intrusive questions/making references to things that require special perception/using magic on surroundings to see if they sense it?
Charlie's demeanor changes when he picks up that he's been found out, but this isn't an issue at all! I'm happy to explore any CR opportunities. tl;dr yes