Gan Takada, commonly called Gan-chan, stands as a central figure in the narrative. The son of a renowned toymaker, he inherits a sharp mechanical aptitude, showcased by his completion and refinement of his father's unfinished project: the dog-shaped rescue robot Yatter-Wan. This skill extends to building and modifying various crime-fighting mechas. He typically wears a blue jumpsuit over a black unitard, paired with a matching blue cap. For his superhero identity, the suit reverses to white, and he adds a red mask, gloves, and a black hat.

Driven by a fierce sense of justice, Gan-chan pursues antagonists with relentless determination, seldom showing them sympathy. Generally reserved, he occasionally displays cheekiness and is easily flustered. Earlier narrative iterations highlight a careless streak and a knack for frustrating those close to him, though he eventually outgrows these traits. A dedicated and skilled mechanic, he is also known for his substantial appetite in certain adaptations.

His main weapon is the Kenda-Magic, a modified kendama that functions as a flail, grappling hook, and electric shock device. He also employs the Karu Koma, a curling top that disorients targets by spinning them, and the Shuru Shuru Cutter, a beam-emitting tool for cutting metal, though these see less use.

Gan-chan works alongside his close partner, Ai Kaminari, and their robotic companion, Omotchama, to thwart the Doronbo Gang’s attempts to assemble the Skull Stone, believed to reveal a vast gold deposit. Despite their efforts, the gang eventually collects all fragments, only to learn the Skull Stone is actually their commander Dokurobei’s true form, seeking reassembly. This leads to Dokurobei’s departure and a peaceful resolution with the reformed gang.

In later stories, Gan-chan and Ai are married. Their honeymoon is interrupted by the Doronbo Gang’s resurgence, which they promptly address, with Gan-chan rescuing a defeated antagonist, Jun the Swan. A subsequent arc reveals Dokurobei returned multiple times for revenge, ultimately killing Gan-chan and Ai. Dokurobei then assumes control of Earth as "Lord Yatterman," twisting the heroes’ legacy. Generations later, their story inspires new protagonists, Galina and Alouette, who take up the Yatterman mantles to oppose Dokurobei’s regime and avenge the original duo.

The character also appears in crossover media like the "Tatsunoko vs. Capcom" video game series, portrayed as a swift but fragile combatant who uses the Kenda-Magic in battle and summons Yatter-Wan for special maneuvers. His game endings show him recruiting fighters from other franchises to form an expanded team and participating in events based on other animated specials.