Kyuzo was originally trained on the Special Forces branch of the Red Fleet to be a "Zero": A stealth fighter transported into the bowels of skyfurnaces to destroy them from the inside out. Marcus Antares got Kyuzo transferred to the Sorcery Corp as a "Guardsman" to protect the warkasters, specifically to protect Marcus beloved, Maya Antares. Secretly, chivalrously, in love with Maya himself, Kyuzo agreed. He followed Maya and the rest of the crew into rebellion and the Storm of Souls. He has quickly developed a paternalistic relationship with the rebel Makita.
Kyuzo is a highly skilled hand-to-hand combatant and weapons master.