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?

'Spirit' is probably the closest. Or something similar to a Persona himself. He's a manifestation of emotions + energy, kind of.

Does your character carry any manner of object or artifact that might ping as being related to spirits, demons, the underworld, etc?

Nope.

Are you okay with Matoba sensing your character's inhumanness/their ability to see/their magical or spiritual artifact?

Sure!

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?

Also fine! Probably nothing will ping him unless Matoba has a way of invoking something "otherworldly"/portals but he's free to prod.