Professor Shiki, referred to in Japanese as Dr. Shiki, is a supporting character in the anime Hyōga Senshi Gaislugger. He is the director of the National Geological Research Institute, an organization that presents itself to the public as a government geological survey body but is in reality a covert frontline base for the cyborg warriors known as the Guyslugger. The institute houses their combat craft, the Solon, and serves as the center of their operations against the Inbem alien invasion. In the modern era, Shiki acts as the team's sponsor and guardian, officially taking responsibility for the warriors after they awaken from thirty thousand years of suspended animation beneath the Antarctic ice.

His personality is that of a knowledgeable and well-meaning man, described as a good-natured figure who is nonetheless capable of scolding the team sternly when the situation calls for it. He functions as a mentor and dependable adult presence for the young cyborgs, providing them with a base of operations, logistical support, and steady guidance as they wage a war that has long outlived the homeland they were created to protect. His scientific perceptiveness is shown early in the series: when the newly awakened Guyslugger first speak in the language of the ancient Solon kingdom, Shiki realizes that they are using a tongue completely foreign to the modern world. His recognition of this prompts the warriors to activate the automatic translation systems built into their cybernetic bodies and converse in fluent Japanese.

Shiki is linked to the team through personal history as well. The dog Jiro, who is mortally wounded during an Inbem attack and later revived as a cyborg dog and full member of the Guyslugger, was originally Shiki's beloved pet. His household also includes his daughter Reiko, a high school student, and a young son, who is around seven years old and turns eight in the final episode; the boy bears a strong resemblance to Ken's younger brother Kou, though the series does not explicitly establish a blood relationship between the Shiki family and Ken.

Shiki possesses no combat abilities himself, but his role is essential to the team's mission. As a civilian scientist and administrator, he anchors the Guyslugger's activities from behind the scenes, maintaining the cover story of geological research while secretly supporting the fight against the invaders. His knowledge, firm but caring manner, and growing investment in the team make him a stabilizing presence for warriors who have lost their homeland and face their battles in a world far removed from the one they originally knew. His development over the series is defined by his deepening commitment as their guardian and his personal connection to Jiro, which ties his own household directly to the fate of the Guyslugger.