Height: 164cm Gender: Male Species: Human Age: 12 years old Personality: He has an altruistic and kind nature, treating Metal Cardbots as true friends. He is mentally strong, cheerful, and active. He is not forceful. Characteristics: He is the chosen owner of the Metal Breath and considers helping others a priority. He has blue hair and blue eyes. Like a typical 12-year-old, he enjoys soccer and riding bicycles.

Height: 165cm Gender: Female Species: Humanoid Age: 12 years old Personality: On the outside, she is quiet, calm, and blunt, but inside, she loves helping others and has a strong spirit of sacrifice. Characteristics: She is another chosen owner of the Metal Breath. Her spirit of sacrifice is so strong that she often neglects her own well-being. She has mint-colored short hair and yellow eyes.

Robot Mode Height: 5.5m Gender: Male Species: Metal Cardbot Vehicle Mode: Police Car Personality: Just, cautious, and deeply affectionate. He has a strong desire to cherish and protect Jun, though he sometimes acts eccentric due to his lack of adaptation to Earth's culture. Characteristics: He views the Metal Breath as a symbol of friendship and is fiercely protective of Jun, unable to tolerate Jun being in danger. He was a Star Guardian (equivalent to a police officer on Earth) on Planet Machina. He is sealed by Jun. His Weapon Cards include Alpha Armor and Howl Gauntlet.

Robot Mode Height: 5.4m Gender: Male Species: Metal Cardbot Vehicle Mode: Ambulance Personality: Cautious and blunt. He is not easily swayed by emotions, but he is a skilled healer with a tsundere-like personality. Characteristics: He views the Metal Breath as a symbol of friendship and is fiercely protective of Jun, unable to tolerate Jun being in danger. He was a military doctor serving in the 13th Unit of the Star Guardians on Planet Machina. He is sealed by Jun. His Weapon Cards include Mega Forceps, Forceps Shock, and Forceps Crush.

Robot Mode Height: 5.9m Gender: Male Species: Metal Cardbot Vehicle Mode: Ladder Fire Truck Personality: Usually timid and honest, but in the face of a fire or emergency, he is a brave character who plunges in to extinguish flames more boldly and seriously than anyone else. Characteristics: He views the Metal Breath as a symbol of friendship and is fiercely protective of Jun, unable to tolerate Jun being in danger. He was a firefighter on Planet Machina. He is sealed by Jun. His Weapon Cards include Aqua Cannon and Fire Hammer.

Height: 178cm Gender: Male Species: Human Age: 28 years old Personality: He has a warm heart. Upon hearing that the Metal Cardbots had nowhere to go after their home planet Machina was destroyed, he even shed tears and decided to help them. He has a strong sense of responsibility as an adult, always going along with the children's plans until the end. Characteristics: He thinks of Jun like a nephew and tells Jun to call him 'Hyung' (older brother) whenever Jun calls him 'Mister'. He has brown hair and a muscular build. He works at a car repair shop and is very skilled at repairs and maintenance.