Mariko is a “ghost”, at least, he’s labeling himself as one. Mariko is actually a human, obsessed with the occult. He even cut off half of his hair for a weird circle summoning! People who knew him before he got obsessed find it so odd how unnaturally quick he seemed to hyper-fixate on the supernatural, so quick and deep that they seem not to even believe it! Being the only human in a group of demons is a little dangerous for obvious reasons, and he’s not sure how long his ghost front would last, so he’s just trying to find his way back home.