We had a M.O.N agent who was basically 'slime monster infected woman' and status was on air as she is both human and a monster same time (two entities in one). Same could called for humans possessed by demon/ghost full time. Status wise they often belong to M.O.N staff (for ease how they can be either in status so they can handle both human and monster jobs), but if asking it depends which party is more dominant/active (or in sense human possessed by ghost is thus ghost's host by default).