Kotetsu's Grandpa is a jackal character and a key influence on the protagonist's aspirations. His deep childhood fascination with space led him to create space-themed manga throughout his career. This background directly inspired his grandson Kotetsu to dream of becoming an astronaut, with the grandfather actively fostering this ambition. He communicates with occasional dramatic or exaggerated expressions, sometimes surprising Kotetsu. As a familial mentor, his lifelong enthusiasm for space exploration and development fundamentally motivates Kotetsu's goals. Within the narrative's anthropomorphic animal universe, he is a jackal. His role is consistently supportive, emphasizing encouragement and sharing his space-related interests without significant evolution or expanded backstory beyond his established background.