Yoshiya Kiryu

Yoshiya, an intelligent and sly teenage boy, prefers to go by the name Joshua and appears to know more about the Game than he lets on.
He is later to revealed to be the Game's Composer, taking the human form as to monitor but not interact directly with the Game. Neku partners with him during the second week of the Game. Uses his cell phone and, later, beams of light from the sky to fight.

(Source: Wikipedia)