Is your character any manner of spirit, youkai, demon, or otherwise inhuman being? o yeah. hua cheng is one of the four great calamities of his world, a supreme-ranked ghost king, super powerful scary eldritch horror etc. etc. his energy is kind of alternatively referred to as ghostly and demonic throughout the novel, but i take it to mean that he pings decidedly nonhuman with pretty murdery vibes.

If your character is human, is your character capable themselves of sensing spiritual energy, youkai, demons, etc? Further, do they have harnessable spiritual powers? he is not human but he is shown to be capable of sensiting spiritual energy!

Does your character carry any manner of object or artifact that might ping as being related to spirits, demons, the underworld, etc? other than his whole general self, nope!

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

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)? go for it! he doesn't particularly hide what he is though so it might be a short test...