L is a mysterious investigative genius who has helped the ICPO with its most difficult cases. He has solved every case he has attempted and solved some of the greatest mysteries the world has ever known. His true name is not known, and the only person that can contact him is Watari whose name is also unknown. He has always appeared to police forces as a stylized letter L on a laptop screen held by Watari. When speaking this way, his voice is distorted to help protect his anonimity.

In the course of the Kira investigation, L decided to reveal himself to the investigation. Only a criminal as dangerous and elusive as Kira could pull him out of secrecy. He sits with his feat in his seat and never wears shoes. He claims that sitting in another position would decrease his reasoning ability by fourty percent.