Hanzo is a stealth assassin under the command of Black Phantom, who behaves and lives under the codes of ninja such as hidding his face behind a mask, wear a full body light armor, and wielding ninja weapons such as a ninjato and shuriken.
Hanzo was sent to protect Black Phantom's secret dealings with Raremetal.
During a private flight, he killed two contacts onboard to prevent their from revealing information to B.A.B.E.L. agents, and he downed the aeroplane with Fujiko, Minamoto and Shūji Sakaki in, upon landing, Hanzo engaged in prolonged combat with Fujiko in the middle of a savannah in Africa .
With the fight affecting the both of them in hunger, thirst, and the need to dispose of bodily waste, they were interrupted by a herd of water buffalo, and the hitman escaped in the confusion.
Having found a moment to relieve himself, Ninja Hanzo was attacked by a water buffalo containing the soul of an animal specialist esper but survived.
Later, he sends a SOS to Black Phantom (Leader) but even though heprevented the leak of information, after being somehow defeated by B.A.B.E.L. he is not only left by Black Phantom, but also he was ordered 'to die'.
Despite this, Hanzo's brainwashing does not seem to be very strong, as instead of suiciding, in the omake panels, he tracks Yuri in Japan and asks her to give him refugee.
Since there Hanzo remains out of sight when the Yūri Kumoi personality is awake, and secretly helps out with her chores such as cooking.
His new task is shared with Nai, they became partners both of them fighting as ninja agents, and eventually started to behave like brother an sister. Hanzo would seek to help to remove the bomb inside Nai, anobjective wich was only possible with the united efforts of B.A.B.E.L. and P.A.N.D.R.A. being the later the caretakers of Nai during the process.
After the revealing of Yuri as the Phantom Daughter, she exiles herself in seek of piece of mind, a grateful Hanzo follows her unconditionally, and ends up joining Blue Star Organization, when he still takes care of Yuuri Kumoi, Nai and Yugiri who joins to the group.
During the suplements is shown that much like the other released members of Black Phantom (Bullet Silver, Tim Toy, and Patty Crew) Hanzo is an Otaku, wearing shirts of a fictional character called "Maruto Ninpuden" an ovious reference to the real life Naruto