Best way to spot an oni is watching how they act when players are nearby. They get really active throwing stuff around and messing with doors way more than usual ghosts, and if you're keeping an eye on sanity levels you'll notice they drain twice as much (20%) when they hit you during events.

Something interesting about these ones is they love showing their full ghost form instead of doing that misty cloud thing other ghosts do. When they manifest, there's actually a 66% chance you'll see their whole body which is pretty unusual. During hunts, they're also easier to spot since they don't flicker as much as regular ghosts do, making them stay visible longer.

You might wanna watch for a few key things to be totally sure - they never do that airball event where ghosts turn into a hissing cloud, and they get super active when multiple people are around. If you're seeing these patterns plus your evidence points to emf 5, freezing temps, and dots, you're probably dealing with an oni. Just remember though, that some other ghosts like poltergeists can be pretty active too so make sure to check all the signs before making the call.