Kotetsu is an anthropomorphic yellow jackal who wears goggles, a red coat, a white shirt, and blue pants. His grandfather, also a jackal, fueled his childhood fascination with space through stories and manga about exploration, directly inspiring Kotetsu's dream of becoming an astronaut. This ambition drives him as a first-year student in the Pilot Department at the Animal Kingdom Space Academy, where he diligently trains and studies to reach space.

Personality-wise, Kotetsu blends seriousness with cheerfulness, tackling challenges with determined optimism. He loves gummy bears, lemon soda, and grilled meat. At the academy, he forges close friendships with fellow students: Lou, a bear focused on rocket science; Hikaru, a rabbit passionate about stellar hospitality; Otama, a cat aspiring to be a space chef; and Niko, a German Shepherd who excels academically. These bonds highlight collaborative dynamics and mutual support among peers pursuing space careers.

Kotetsu's grandfather remains a supportive figure, occasionally offering exaggerated but encouraging remarks that bolster his resolve. His consistent portrayal focuses on diligent training, camaraderie with classmates, and steadfast commitment to his astronaut ambitions within the academy environment.