>>280929102
This ougi classmate who transferred from nowhere ambushes him and then keeps following him around heckling him like a cheeky tulpa, even trying to kill his friends sometimes. That's possessed as fuck. The proof is in the shadows and in the "internal voice" sound effects. And in the character arc, Ougi is explained at the end, it's Araragi's oddity.
I'm omitting the kiss shot affair here obviously. It's not the same.