Duncan

"“I am the Imperial Demon General Duncan… the Space Demon King's most loyal subordinate!” —Duncan, introducing his true self" The General Duncan (ダンカン将軍) was one of the main antagonists of the film Tetsujin-28: (Un)Fortunate Son and the commanding general in charge of Space Demon King's imperial demonic armies. On Earth, he masterminded the kidnapping of former Taimanin in the guise of an unknown human to strengthen his demonic army.

Personality
Duncan has a cold and calculating personality with the interest to execute plans with nobody noticing. He can also recognize a significant threat an enemy could pose, such as when he recognized the Earth's forces' potential to repel invasions from various other alien factions, and thought the only way to break apart the forces of the planet and subjugate their targets was to do it from the inside.

Tetsujin-28: (Un)Fortunate Son
The Space Demon King feared that with the potential of Earth's forces in great power that they demonstrated in the last years, and previous pushbacks against many alien armies such as the Boazanians, Campbellians, Gishinians and more, the planet would not be an easy planet to conquer. He sent his right-hand man and general Duncan to Earth to make sure the enemy fighting force falls apart from the inside. After researching for a few years on the various Earth factions, he concluded that one of the major obstacles that prevent Earth's downfall are the Taimanin. Henceforth, he devised a plan of kidnapping married ex-Taimanin as phase one, which had been occurring for a few months. The disappearances caught the attention of many Taimanin groups and other heroic organizations, including Karin Sugita who was sent to investigate.

Quotes

 * “I am the Imperial Demon General Duncan… the Space Demon King's most loyal subordinate!” (俺の名は皇魔将軍ダンカン…！宇宙魔王様の忠実なる部下だ！)