0016 is a hulking man with a body that has been completely remodeled into a cybernetic chassis. Like the other "High-Teen Number" Cyborgs his uniform is made of tight fitting black cloth, with four large oval buttons on the chest. He wears knee length boots with red trimming and a long white scarf around his neck.
Before his conversion, Smith is shown to have been a tall, muscular dark skinned man with black buzz-cut hair and brown eyes.
0016 seems to have been built as an all out war machine, similar to 004. He possesses super-strength capable of matching 005 in battle. He can launch missiles from his head, shoulders, and even from ports in his chest that are unveiled by him manipulating the buttons on his uniform to open up. The synthetic flesh on his hands also shreds as his arms explode open to reveal his more obviously robotic plasma cannons.
As he also bears an Accelerator, he is very fast in battle and can use it to practically vanish from sight.
0016 is a silent man, possibly unable to speak at all due to his status. When being introduced, it is 0014 that has to identify him as "Cain" to the 00 cyborgs.
He is often seen hanging around 0017 and letting the child ride on his shoulders. When 0017 is violently killed in the climactic battle, he instantly attempts to avenge the younger cyborg, only for his attempt to result in his own death.
In his past, he had been a soldier known as the captain "John Cain Smith" and had clashed with the 00 cyborgs before, particularly 009.
Now simply dubbed "Cain", he was input as the third subject of Dr. Adams' project and would lose his entire body in the process, only retaining his brain as the organic component and reminder of his former humanity and self. The technology used for his chassis and weapons would be the same used for the Mad Machine M-1 device that the 00 cyborgs had went up against in Antarctica.
During the sightings of demons in Japan, 0016 and his fellow team member 0017 would be seen observing Akira Fudo and Miki Makimura on their way to school. The two, with 0014, would later watch and confront 002, 004, and 008 in their investigation into demon activity.
The three High-Teen Numbers would do battle against the 00 prototypes, with 0016 taking on 004, until they would soon depart, having only battled the prototypes to collect data on their abilities.
The two cyborg factions would reunite later, when the 00 cyborgs made it to Dr.Adams' Black Ghost base and the High-Teen Numbers were prepared for a longer, more brutal fight. 0016 would single out 005 to fight, but would also attempt to shoot the cyborgs with his missiles and be foiled by their Super Guns. He would also be challenged by 004 and 008.
Ultimately, the battle became complicated and interrupted by the arrival of Devilman and the demon Atun, who had overtaken the body of the High-Teen Number cyborg 0018. Though his sister 0015 would attempt to return him to normal with a shockwave attack, this would be a false alarm as the seemingly newly-angelic 0018 would soon lay waste with his powers and declare himself "Neither Set nor Atun" (known in supplementary materials as Azazel), with Atun simply having merged further with the young man.
0017 would attempt to charge the gestalt with a razor snowflake, but would be sliced in half and blown up by his own power being redirected back at him. 0016 would instantly be silently angered, attempting to avenge his comrade and attack Azazel in turn, but would be electrocuted by the other's shock waves and have his plasma cannons turned back on himself, blowing him up and seemingly obliterating him entirely.
0017's original name, Cain, comes from the biblical character of the same name, who is infamous as the first murderer in the Bible's lore. Ironically, Cain did not murder 0016 (Abel) but 0016's death did cause 0017's downfall.
- Cain's appearance is partly based on Robot Detective K, a character created by Shotaro Ishinomori.