Iwao Oguro, also known as Knuckleduster and formerly professionally known as the High-Speed Hero: O'Clock or simply O'Clock, is the tritagonist of the 2016 Japanese superhero My Hero Academia spin-off manga series My Hero Academia: Vigilantes.
Oguro was originally a professional hero operating primarily in Japan under the alias O'Clock. His quirk, aptly named Overclock, allowed him to increase the speed of his own perception to the point that the world around him appeared slow. Outwardly, O'Clock's quirk appeared as though it simply accelerated his movements, however it was his increased perception that allowed him to move at impossible speeds. Ultimately however, Iwao's quirk was stolen from him by the legendary villain All For One, leaving him quirkless.
After the loss of his quirk, Oguro abandoned his hero identity to work as a vigilante outside of the law. Although he had no powers, he honed his body and combative abilities to a lethal level that allowed him to go toe-to-toe with professional heroes and villains alike. With a pair of brass knuckles on his hands, Oguro descended to the streets and brought down criminals with shocking brutality. His main goal as the vigilante known as Knuckleduster was to defeat the Villain Factory, a secretive organization turning regular people into monsters using drugs.
Iwao Oguro was a towering man with bulging muscles who stood at six feet and one inch tall. He had black eyes and short black hair cut into a crew cut. He usually had heavy stubble covering his face, although when he left it unkempt it would grow into a thick messy beard of black hair. Perhaps Iwao's most noticeable feature was a prominent scar caused by All For One that ran diagonally down his left cheek.
As the vigilante Knuckleduster, Oguro wore a poorly-cobbled together outfit. His ensemble consisted of a tight-fitting black t-shirt, a long green trench coat, beige cargo trousers, black heavy-duty boots, a pair of black fingerless gloves, and a black mask over the top of his head that kept the top of his head and eyeline obscured. In combat, Iwao wore a pair of brass knuckles over his gloves which he derived the name "Knuckleduster" from.
- Hideyuki Furuhashi, the author of My Hero Academia: Vigilantes, has stated that in the same way All Might can be considered the Superman of My Hero Academia, Knuckleduster can be considered the Batman of My Hero Academia. Superman and Batman represent justice on a societal and personal level respectively, a trait that is reflected by All Might and Knuckleduster respectively.
- Knuckleduster shares several similarities with the aforementioned DC Comics character Batman. Both characters are completely powerless in a profession dominated by individuals with superpowers, both primarily rely on their martial arts skills and tactical intellect to win fights, both take on a pupil who assists them in their crimefighting (Batman's is Robin and Knuckleduster's is The Crawler), both are known for their excessive brutality while fighting crime, both have many years of experience under their belts, both use a variety of tools in addition to their martial arts and keen minds, and both have tentative relationships with the authorities and other superheroes.
- There are several similarities between O'Clock and the DC Comics character The Flash. Both are able to perceive the world with accelerated perception, both wear streamlined full bodysuit costumes with a mask that only leaves the face partially exposed, both are able to move at superhuman speeds, and both have an arch-nemesis (Zoom for the Flash and Number 6 for O'Clock) who idolized them in the past before turning villainous in their pursuit to replace their respective hero. Furuhashi later revealed that the parallels between the characters were intentional, and that O'Clock was directly inspired by the Scarlet Speedster.
- Betten Court, the artist and character designer for the Vigilantes series, enjoyed drawing Knuckleduster the most as of the first volume of the manga. In addition to using the Flash as a reference when designing O'Clock, Court tried to incorporate aspects from the designs of the Residents of the Land of Light from the Ultraman series as they exhibited the orthodox hero impression that was intended for O'Clock.