Well, he would be lacking any sort of heartbeat or breath unless he is aware someone was looking for that. The normal human form is actually a projection, and his true form is that of a black cone. To be fair though, most of the canon cast who are experienced mages and frequently battled various monsters including other Mazoku were not aware of his true nature until much later on, after it is just sort of revealed.

Though enough blabbing on that. Hope you have a fun time here with Ginko. :D