Naoyuki Andō

Naoyuki is Hiro's childhood friend. He acts as Ichiro's informant and assistant after he finds out the true nature of Hiro and help him in his quest to save people and hunt Hiro down, even as far as teaching him the basic of how to control his mechanical body.

He's a big fan of Gantz manga series

Trivia

 * Naoyuki is a big fan of Gantz manga series.