Garan commands one of three rival factions battling for dominance over Machine Island, leading the Garan Army. He utilizes the island's resources to mass-produce war machines, including X-Battler units modeled after classic Mechanical Beasts. His forces and fortress display a distinct feudal Japanese aesthetic, contrasting with the styles of the other warlords.

Physically imposing, Garan wears brown and yellow samurai armor with a red helmet featuring a white dragon motif and a yellow band, complemented by a long black beard and a cape. His personality blends ambition for global conquest with a notably calm and strategic demeanor compared to his rival Kiba, though visions indicate his rule would bring global chaos.

A veteran combatant, Garan demonstrates exceptional swordsmanship, matching protagonist Ken Kaido in a duel, and masterful tactical command during large-scale battles. He pilots the high-speed mecha Geistteles, leveraging its agility to initially overwhelm the Mazinkaiser SKL. He shares a psychic connection with his lieutenant Himiko, enabling communication and mutual awareness of danger.

Garan identifies as an Erbsünde, sharing this mysterious trait with Ryo Magami; his specific origins remain undisclosed. His story arc begins with him observing the Skull Force disrupting his conflict with Kiba. After Ken infiltrates his fortress, Garan engages him in a swordfight before switching to mecha combat.

Exploiting Ryo Magami's rage over taunts about fate, Garan gains an advantage in their first battle, hurling the Mazinkaiser into a trench. During their rematch, however, he senses Himiko's death through their psychic link, causing a fatal distraction. This allows Ryo to fatally pierce the Geistteles' cockpit with the Ganzanto sword. In his final moments, Garan laments that his bond with Himiko cost him victory before perishing in the Geistteles' explosion.