Haguruman is a robot created by the criminal organization BAD, appearing as the final enemy in the series. He is described as the strongest robot in BAD’s arsenal, possessing immense physical strength that allows him to overpower the protagonist K even when K has activated his Blow Up power‑up mode. Haguruman’s primary motivation is to execute the final plan devised by BAD’s leader, which involves transforming the world’s water supply into gasoline to scorch the Earth. He operates as a loyal enforcer of BAD’s will, showing no hesitation in using his abilities to achieve that goal.

His most distinctive ability is the power to transform his body into a large gear. In this form, he uses the gear’s spinning motion to attack opponents and can also employ a rocket propulsion device located at the gear’s center to fly and evade. This versatility makes him a formidable combatant. Haguruman’s role in the story is that of a final obstacle for K and his human partners. He appears in the twenty‑sixth episode, engaging K in a decisive battle that tests the detective robot’s upgraded capabilities. He has no personal relationships outside of his allegiance to BAD, and his character undergoes no development, as he is a one‑episode antagonist whose sole purpose is to serve as the culminating threat of the series.