Insomnium

Long time friends George and Phinneas share a duplex in Los Angeles. Their Russian landlord, Mr. Romanovsky lives in the upstairs unit. George's girlfriend Kim and her friend Olivia come over and after some drinking, they bring out a Ouija board. That night, Phinneas begins to exhibit disturbing nocturnal behaviour. As George investigates more into his friends behaviour, he suspects that his friend has become possessed by a dark entity

It's time you knew about the girl upstairs.