Board Thread:Legitimate Canon Questions/@comment-26742635-20150721085855/@comment-4091815-20150722190642

Oni are spirits that temporarily took on corporeal form - they were able to break through with great effort - just as Scott was.

You're complicating something that the show presents very simply.

They've defined supernatural.

Just because their word "supernatural" doesn't mean what you think it should mean doesn't change the in-universe definition.