In the 2005 film Kamen Rider The First, the character known as Dr. Shinigami is a high-ranking executive of the terrorist organization Shocker. Unlike the original television series where he is a prominent field commander, in this film adaptation he is a more mysterious figure, often referred to as the Shocker Staff Elderly Gentleman. His physical form is largely that of an enigma; he appears to his subordinates and communicates only via satellite feed on screens within Shocker's headquarters, making his true physical whereabouts unknown. When he does appear on these screens, he is depicted as an elderly man with a pale, almost vampiric face, complete with visible fangs, and he wears a long, dark cape, often black and red.

Dr. Shinigami occupies the highest echelon of Shocker's leadership in the film, commanding operations alongside two other major agents known only as the Youth and the Lady. From the very beginning of the narrative, he is shown to be one of the primary architects of Shocker's plans, including the mass production of cyborg soldiers known as Inhumanoids. He is responsible for overseeing the reconstruction and brainwashing of college student Takeshi Hongo into the organization's first Hopper cyborg, who later escapes and becomes Kamen Rider 1. When Hongo becomes a traitor to the organization, Dr. Shinigami authorizes the creation of a second Hopper, Hayato Ichimonji, specifically tasking this new cyborg with the mission of eliminating the first Rider.

In terms of personality and motivation, Dr. Shinigami is defined by his cold, calculating demeanor and his absolute commitment to Shocker's goals of world domination. He shows no empathy for the individuals who are kidnapped and forcibly turned into cyborg soldiers, viewing them purely as tools or assets to be deployed and discarded as necessary. His primary motivation is the success of Shocker's objectives, which includes perfecting the process of creating Inhumanoids and ensuring the destruction of any threats to the organization, particularly the renegade Kamen Riders. He survives the events of the film; after the defeat of several Inhumanoids and the destruction of Shocker's island base, he and the other major agents are revealed to have survived, already establishing a new base of operations and plotting future schemes to eliminate the Riders.

Key relationships for this character are almost entirely professional and hierarchical. He serves as a direct superior to the various Shocker agents and Inhumanoids, including the Bat, Spider, Cobra, and Snake. He has a particularly significant relationship with the two main protagonists, Takeshi Hongo and Hayato Ichimonji, viewing them as his greatest failures and most pressing threats. While he commands them as their master initially, he later brands them as traitors to be exterminated. His role in the story is that of the primary strategic antagonist; he does not typically engage in direct combat himself but instead orchestrates the overarching plot, issues orders, and unleashes Shocker's monsters to fight the Kamen Riders, acting as a persistent and central pillar of the evil the heroes must oppose.

Regarding development and notable abilities, Dr. Shinigami remains a relatively static character throughout the film, maintaining his position of authority and his shadowy, commanding presence without a personal character arc. In terms of abilities, his primary power is not physical combat but his scientific genius and strategic mind. He is depicted as a master of the advanced cybernetics and reconstruction technology that Shocker uses to create its army of Inhumanoids and the Kamen Riders themselves. This version of Dr. Shinigami notably does not transform into a monster form, a departure from the original series character who could become the squid-like Ikadevil. Instead, his power lies entirely in his intellect, his command over the organization's resources, and the fear he instills as a seemingly immortal and omnipresent commander.