Momochi Sandayū is a character from the manga Watari by Sanpei Shirato and its 1966 live-action film adaptation Watari Ninja Boy. Within the story, Sandayū Momochi is depicted as the leader of the Iga ninja clan, a position that places him at the center of the clan's internal power structure. His role in the narrative is closely tied to the corruption that has taken root within the Iga clan. While Sandayū himself is the official head of the clan, much of the conflict in the story is driven by the actions of his scheming vice-leader, who has been responsible for the unjust killing of many ninja. This corruption and the violence committed by his subordinate create the central crisis that the young protagonist, Watari, must confront. Sandayū's position as clan leader makes him a figure of authority, but the story focuses on the betrayal and moral decay occurring under his leadership, forcing Watari to navigate the treacherous internal politics of the clan. His motivations and personality are largely defined by his role as the leader of a powerful but compromised organization, and his key relationship with his treacherous subordinate sets the plot in motion. The character does not undergo significant development within the story, as the narrative primarily follows Watari's journey to expose the corruption and avenge the fallen ninja. Sandayū's notable abilities are implied by his status as a high-ranking ninja leader, but the story concentrates on the conspiracy within his ranks rather than his personal combat or espionage skills. His background as the head of the Iga clan is the foundation of his importance to the plot, serving as the authority figure whose domain has fallen into moral decay.