Kentaro Shiratori serves as one of two central protagonists, sharing both a close childhood bond and identical birth date with his friend Takeshi Kido. Their lives irrevocably shift when attacked by a lake-emerging monster. Facing imminent peril, they are contacted by the entity Kopu, who designates them as protectors against the evil Doruge (alternately called Goumon). This encounter grants them a radar device and the ability to fuse into the superhero Barom One by joining hands, a transformation facilitated by the Barom Brace device. Through fusion, they gain extraordinary combat capabilities like superhuman strength. As Barom One, Kentaro confronts monstrous threats dispatched by Doruge, categorized as Animal and Plant Majin or Human Body Majin. These adversaries exhibit diverse designs and abilities, from Okozeruge (Stonefish) to Hyakumeruge (Hundred Eyes). Kentaro maintains personal ties to his family—Keitaro and Shizuka Shiratori—and interacts with Takeshi's relatives Matsugoro Kido, Rintaro Kido, and Noriko Kido, alongside ally Yuko Sugino. His journey emphasizes partnership, courage, and sacrifice while defending their city and loved ones against Doruge's forces.