A pioneer in both the N.E.T. and Z.E.T. Projects in the Amagi Corporation, Kanzaki escaped with an infant Jin in defiance to turning his 'child' into a killing machine. Later diguised himself as a homeless old man and posed as the grandfather of the growing Jin. Was killed in a bid to protect Jin from an awakened Player.
Kanzaki's head was however retrieved by the Amagi Corp. and hooked up to a computer so as to obtain unknown information about ZET/Jin. Their efforts were in vain however when a crying Jin, unable to bear seeing his grandfather in such a state, pulled off the life support plug, with Kanzaki asking Jin if he had been taking his meals regularly as a final greeting. However, it was revealed that Mitsuagi had the life support plug put back in. His head was then stollen two years later by the Chameleon Player, with the intentions if cracking the secrets in his head.
He managed to make Jin lose his powers of ZET by tricking Mitsugai, but it was brief when the Amagi Corp. came up with a gum which allowed Jin access to his original abilities.
Known mainly as the grandfather of Jin, he lived in the slums with Jin, disguising himself with a long beard, in a house made of wooden planks. His wish was that Jin could grow up as a human, not as Zet or a player. Through deception, he was able to make Jin lose all of his powers as Zet to save him from the clutches of Amagi Corps. His plan failed however when medicines were created to aid Jin turn into Zet (chapter 67).