The World God Only Knows (2010)

Keima Katsuragi prefers immersing himself in the 2D world, chasing digital girlfriends. However, after answering a mysterious email he finds himself bound by a contract helping the demon Elsie capture 'lost souls' from the underworld. He must now win over these real-life ladies in order to fill the void in their hearts which these souls have entered, releasing the souls and allowing for their capture. Also to further motivate, if he does not perform this 'duty' a collar around his neck will explode.