The Grim Reaper and the Heavenly One

Pontifex Lembrary is widely regarded as having the most powerful divine power ever. While he fights against a devil, he gets transferred to a different world. Pontifex Lembrary then finds himself in a small dormitory and possesses the body of Woo Yeon Woo, who is a member of the unpopular idol group Wild Animal. The group has been together for 3 years, but they are on the verge of disbanding due to their lack of success. 9 hours later, Pontifex Lembrary is placed on a stage with Wild Animal for a live performance at a broadcasting station. When the music begins to play, Pontifex Lembrary, in Woo Yeon Woo’s body, shouts out, "I don't know how to dance." The live broadcast performance is a disaster, but it attracts the attention of people and the media.
And somewhere in the after life there is Sa Gam Jae, a cold grim reaper who also is a secret investigator and is trusted by the king of the underworld to do his job properly.