Ishikawa Ango is a detective with smarts and a keen sense of observation. He's in a great physical shape and also highly ambitious. Ango also only focuses on his work and his personal life is pretty much non-existent.
One day, a former police officer is killed by a gun shot. Ango goes to the scene of the crime, but is shot in the head by the killer who is lurking at the crime scene. Ango hovers between life and death. At that time, he thinks to himself "where do people go after they die?" and then "I don't want to die." A miracle then happens. Ango survives with the bullet still lodged in his head. He goes back to work.
A new murder case takes place. When Ango goes to the crime scene he notices a boy who looks like he is about to cry, but only Ango is able to see the boy. The boy is the one who was killed. Since Ango was shot, he can now see and talk with the dead.