Mamoru Sagami is a resident of the isolated steel-mill town of Mifuse and the father of Mutsumi Sagami. Before the catastrophic explosion at the mill in January 1991, he worked as an employee at the factory and also served the local shrine. In the aftermath of the disaster, which trapped the town in an eternal winter and froze time for its inhabitants, Sagami emerged as the dominant authority figure. He interpreted the explosion as divine punishment for mining a sacred mountain and convinced the townspeople that their survival depended on maintaining their pre-disaster identities without any change. To enforce this, he created a system of periodic identification forms and declared that the factory had become a Sacred Machine of the gods, releasing a smoke that took the form of a wolf. This smoke, which he called the Sacred Wolf, was said to seal the cracks that occasionally appeared in the sky.

Sagami’s personality is marked by loneliness and a deep-seated fear of being erased. Having long been pushed away by others, he found genuine joy in small gestures of friendship, such as when Akimune Kikuiri referred to him as a friend. Despite this, his approach to protecting the town was driven by selfishness and terror rather than genuine care for the community. He used his knowledge of the shrine and the factory to present himself as the only one who understood the gods, and the townspeople, though uneasy, followed his lead out of desperation.

His primary motivation was survival at any cost. When a feral girl named Itsumi was discovered living in the factory’s fifth furnace, Sagami insisted that she was a woman of the gods sent to preserve their world. He feared that if Itsumi left, the townspeople would vanish from existence. Consequently, he confined her to the factory, robbing her of any chance at a normal life. He later formed a cult around her, claiming that worshiping her was necessary to maintain their illusory peace.

Sagami’s role in the story is that of the main antagonist. He represents the town’s resistance to change and its desperate clinging to a false reality. His key relationships include his strained bond with his daughter Mutsumi, who eventually sides with Masamune Kikuiri to free Itsumi, and his uneasy alliance with Akimune Kikuiri, whose pragmatic suggestions to send Itsumi home he overrules. Sagami also stands in opposition to Masamune and the younger generation, who yearn for a real future.

Throughout the film, Sagami’s development is limited; he remains steadfast in his beliefs even as the truth about their world—that they are all phantoms existing in a constructed reality on the brink of collapse—comes to light. He orchestrates a ritual to offer Itsumi to the Sacred Machine, but Masamune and Mutsumi disrupt it and place Itsumi on a freight train bound for the real world. Despite Sagami’s efforts to stop them, he fails. The ultimate fate of Sagami and the other townspeople is left ambiguous, though it is hinted that they may have returned to the real world along with Itsumi.

Sagami does not possess supernatural abilities; his power lies in his persuasive speech and his position as the head priest of the shrine, which he uses to control the frightened populace. His notable skill is his ability to craft a religious narrative around the disaster, effectively creating a cult that enforces stagnation. However, his actions are ultimately revealed to be based on a lie, as the Sacred Machine and the gods were fabricated explanations for their trapped existence.