Doctor Carter, also identified as Commissioner Tsukikage or Takeshi Tsukikage, commands Blue Fixer, Earth's military defense organization. He leads the defense against the S-1 invasion forces, overseeing operations involving the space warrior Baldios and coordinating strategic responses to threats like General Gattler's attacks. His responsibilities include managing personnel such as Marin Reigan, Jamie Hoshino, Jack Oliver, Raita Hokuto, and researcher Ella Quinstein while making critical decisions during planetary crises.

During Gattler's assault with artificial suns melting Earth's polar ice caps, Doctor Carter directs Blue Fixer's efforts amidst catastrophic flooding and mass casualties. He authorizes removing a radioactive core from the World Union submarine base to prevent further contamination, leading to its deployment against the Aldebaren fleet. This action eliminates Gattler and his forces but results in Carter's death alongside enemy troops. His leadership extends to scientific oversight, collaborating with Dr. Quinstein on hyperspace research and countermeasures against S-1's technological advantages. In the film adaptation, he remains present during the final confrontation between Marin and Gattler, maintaining operational authority within Blue Fixer's command structure.