Musculator, whose real name is Suguru Kinniku, is the central protagonist of the Kinnikuman series. He is a superhero from Planet Kinniku, a world known for producing the universe’s greatest superhumans, but he initially appears as a clumsy, foolish, and comically inept individual. Despite his muscular build and heroic aspirations, he often fails at basic tasks and is more interested in eating and goofing off than in serious combat. His true identity is that of the missing prince of Planet Kinniku, a fact he learns early in the story. Because of his incompetence, he must prove himself worthy of the throne by participating in wrestling competitions and battling evil beings known as Chojin.

Musculator’s personality is a blend of immaturity, laziness, and unexpected courage. He is prone to overeating, making foolish decisions, and relying on luck, yet he possesses a deep-seated sense of justice and loyalty to his friends. When the situation becomes dire, he can tap into a hidden reservoir of strength and determination, often surprising both allies and enemies. His primary motivation is to earn the respect of his father, King Mayumi Kinniku, and to protect Earth and his loved ones from threats. Over the course of the series, he grows from a bumbling failure into a capable and respected hero, though he never entirely loses his comedic flaws.

In the story, Musculator serves as the lead hero who must overcome increasingly powerful villains in wrestling-style battles. He participates in major tournaments, such as the Choujin Olympic and the Throne Succession arc, where he defends his claim to the Kinniku throne against other pretenders. His key relationships include his loyal friend and assistant Meat Alexandria, his rival-turned-ally Terryman, the stern but caring Robin Mask, and his father Mayumi Kinniku. He also forms bonds with former enemies like Ramenman, Buffalo Man, and Warsman, who become trusted comrades. His development is marked by his gradual mastery of his inner power, known as his “burning fighting spirit,” which allows him to evolve and surpass his limits in each battle.

Notable abilities include a variety of wrestling techniques, such as the Kinniku Buster, Kinniku Driver, and Muscle Spark. He possesses immense physical strength and endurance, and he can access a secret power called the Face Flash, which is triggered when he removes his mask. This ability can heal allies or purify evil influences. He also has the potential to transform into a giant form under certain conditions. Although he is often portrayed as a comedic character, his fighting prowess becomes legendary, and he eventually passes on his legacy to his son, Mantaro Kinniku, in the sequel series.