Doburai, also known as Space Emperor Doburai, is the supreme ruler of the Waldastar forces, the primary antagonistic alien race seeking to conquer Earth in the original anime series. His background is shrouded in mystery; his appearance is distinctly non-human, and he is only ever seen as a projected image, keeping his true physical form hidden. This has led to speculation that he might be an energy-based lifeform, though this is never confirmed within the series. He commands his forces from a distant location, presumably a base or homeworld, and orchestrates the invasion of Earth through his subordinates.

Doburai possesses a tyrannical and impatient personality. He is frequently shown to be enraged by the repeated failures of his field commander, Rambos, often punishing him for his incompetence. As the series progresses and the Waldastar forces continue to suffer setbacks, his frustration builds, eventually turning into a silent exasperation. His primary motivation is the conquest and subjugation of Earth, a goal he pursues relentlessly. He acts as the distant, shadowy mastermind behind the Waldastar war effort, setting the overall strategy of invasion while his underlings carry out his will on the front lines.

Doburai’s most significant relationship is with his subordinate, Rambos, who serves as his primary agent and is the frequent target of the Emperor’s displeasure. Rambos is responsible for leading many of the Waldastar operations, and his constant failures are a source of great frustration for his master. Doburai does not have a direct physical relationship with the series' protagonist, Tekkaman, as he never engages him in person. Instead, he acts as the ultimate goal for the hero, the central figure of the enemy regime that must be defeated to end the war.

The character does not undergo any significant development within the series proper. He remains a static, mysterious antagonist whose nature and true form are never revealed. Originally, plans for a third story arc of the anime, which was never produced, would have included a reveal of Doburai's true nature, suggesting that his hidden form was intended to be a major plot point that ultimately went unexplored. While his role in the original story is that of a distant commander, a later appearance in the fighting game Tatsunoko Fight expands on his capabilities. In this game, he can enter combat by calling Tek-Setter and equipping armor to transform into Tek-Set Style. In this form, his special attack is a powerful energy blast called the Voltekka, a reference to his implied formidable power. His abilities in the original series are not explicitly detailed, but as the supreme ruler of the Waldastar, his authority and implied power are his primary attributes.