Duke Saturn, alias Hiro Tsuchiya, commands authority as a high-ranking operative of the Inma Empire, an antagonistic organization dedicated to reviving Apollo, the god of lust, and imposing global control through corrupt methods. Masquerading as Hiroto Tsuchiya, a respected English instructor at Golden Star Academy, he conceals his true identity while infiltrating human society to advance the empire’s agenda.

Holding the title of omni-man within the Inma hierarchy, he wields expansive jurisdiction to orchestrate and supervise the empire’s sinister schemes. His allegiance lies solely with Empress Necros, and his history intertwines inextricably with the empire’s pursuit of locating the Venus Warriors by detecting their concealed markings, though his personal origins remain undisclosed.

Duke Saturn’s role remains unchanging across documented narratives, devoid of personal evolution or backstory. He collaborates with fellow Inma Lords—Count Uranus, Viscount Neptune, and Baron Pluto—to deploy tactics such as dispatching goblin-like scouts and targeting the Venus Warriors. His portrayal remains uniformly consistent as a secondary antagonist, strictly devoted to executing the empire’s mission without deviation or expanded exploration in alternate media or spin-offs.