Operating under the alias Saitani Umetarō, the historical Sakamoto Ryōma maneuvers within the anime's Bakumatsu period as a political opponent of the Tokugawa shogunate, leveraging his connections and influence. His past collaboration with Hiwou's father, Masurao, established a protective bond with Masurao's family following the man's departure. This drives Saitani to act as a strategic ally and guardian figure for Hiwou and his companions during their journey.

He provides essential guidance, logistical support, and safe passage, particularly against the antagonistic Wind Gang, honoring his promise to Masurao. Saitani intervenes critically using his network and resources, mediating tensions and offering counsel during the group's encounters with political factions. While deeply engaged in political maneuvering against the shogunate, he holds a philosophical opposition to weaponizing clockwork technology, contrasting the Wind Gang's militarism and aligning with the protagonists' pacifism. His backstory involves Masurao's coerced role in the assassination of Ii Naosuke, an event shaping Saitani's critique of extremism and his advocacy for measured political change. His choices consistently favor peaceful resolution within the turbulent era.

Saitani's interactions extend to adapted historical figures like Shinsengumi members and other Bakumatsu personalities, contextualizing his role navigating the period's politics. He consistently champions openness to Western ideas and technological progress, opposing isolationist policies, reinforcing the series' themes of cultural change during Japan's feudal transition.