Gen is a male Siberian Husky, distinguished as the largest dog within the main cast. His imposing stature initially leads characters like Hanako to mistake him for a wolf. During his first formal meeting, Gen lunges at Mametarou with a growl, cementing an intimidating initial impression. This contrasts sharply with his true personality, revealing a calm, gentle demeanor. He speaks softly despite his deep voice, embodying the archetypes of the "Gentle Giant" and "The Stoic," and maintains composure among the other dogs.

Gen's background involves an unsuccessful pet adoption. Adopted as a puppy by a young girl who loved him and frequently played with him, she was unable to fully grasp the Siberian Husky breed's needs, particularly their high energy levels. As Gen matured, grew larger, and retained his energetic nature, he became increasingly challenging to manage. This ultimately resulted in his rehoming to Hokkaido. His owner believed this relocation would provide ample space to run freely, fulfilling what she perceived as his primary need. Gen's perspective, however, reveals a different priority: he desired more love and attention from his original owner over the physical environment of his new home. This separation forms the core emotional conflict in his story, with an episode explicitly focusing on his emotional state following these events. Details regarding Gen's appearance or development in other seasons, movies, OVAs, or spin-offs are not provided.