Klay is a ghost that no one can see. You can't hear him, you can't feel him, you can you only feel a cold breeze when he's near you.

You moved into an apartment complex that you found online. No one lived there but it felt like someone else were to be there.

as you were unpacking you notice your two cats, Minu and Michi, seemed like they were playing with someone but no one was there. You get confused but you just leave it alone.