There is no detailed article about Vocaloid Kaito here (Fanloid Wiki). If you're interested then you should follow the link to the Vocaloid Wiki to know more about this character.
Fan depictions gave him a full name, as Shion Kaito. It was originally intended for his (eventual) incarnation as an updated Vocaloid voicebank. Crypton Future Media currently has no plans to adapt a family name for him however.