The character known as Octavo Hombre, also called 8 Man, is the cyborg protagonist of the anime 8 Man, and the figure referred to as Yodoka Azuma corresponds to the same person across the different tellings of his origin. In some versions his original name appears as Yokoda or Yokota. He begins as a Tokyo police detective who is killed in the line of duty: in the television series he is struck and run over by a car, while in the original manga he is trapped in a warehouse and gunned down by criminals. His body is recovered by a scientist, Dr. Tani in the anime, who had previously attempted a similar procedure seven times without success. In Azuma's case the transfer of his consciousness into a powerful android body finally works, and he is reborn as the armor-skinned cyborg 8 Man.

After his rebirth he takes on a civilian identity as the detective Hachiro Azuma and continues to fight crime, effectively serving as a secret eighth division of the Tokyo police alongside Chief Tanaka, his only superior. A central part of his character is that he keeps the truth of his robotic nature hidden from almost everyone, including his secretary and love interest Sachiko and his assistant Ichiro. He typically presents himself in the form of his former human body, so that his transformation is not obvious to those who knew him before. His personality is defined by the sense of duty he carried as a policeman; he is motivated by a desire for justice, by the need to protect people in danger, and by the resolve to bring criminals, including his own killers, to account. His dual existence as a man with a human past and a machine body shapes his conduct throughout the story, as he carries the burden of his secret alone while trying to live an ordinary life in his civilian role.

His abilities are far beyond those of an ordinary person. He can run at impossible speeds, fast enough to keep pace with a train, and possesses superhuman strength and durability. He can also shape-shift, altering his appearance to resemble other people, which serves him well in investigations and confrontations. When he overexerts himself and his energy runs low, he recharges by using special power cigarettes, capsules disguised as ordinary cigarettes that he carries in a case on his belt and draws on to restore his strength. The name 8 Man itself is explained in the source material either as a reference to the military designation 008 given to his android body or as a nod to his role as an unofficial eighth force alongside Tokyo's seven police precincts. Over the course of the series he faces a wide range of superhuman villains and criminal schemes, and the tension between his heroic work and his concealed android identity remains a recurring element of his story. In later continuations of the franchise, the original character eventually disappears, and the mantle of 8 Man is passed to another officer killed in the line of duty, continuing the legacy he began.