The World God Only Knows

The main charecters are Elsie (Last name not known) and Keima Katsuragi

Keima is 17 years old and Elsie is a demon from (new) hell

Keima has to help elsie by "conqering" girls with loose souls and the loose souls are captured (By elsie) usually after a kiss

The collar around keima's neck will activate if he breaks any of the rules. The punishment will also apply to the Buddie/Demon (Elsie in this case as she is keima's buddy)