Kentaro Takaoka debuted in the 1969 *Tiger Mask* anime as Yellow Devil, a wrestler for the villainous Tiger's Den. Born into poverty in Meiwa, Gunma, he supported his sick mother and younger sister through milk deliveries after his father's death. Recruited into the Tiger's Den at age 15 by Mr. X for his karate skills—showcased when he smashed a table with a single chop—he later attempted escape due to homesickness. Following his mother's death, believing Tiger Mask responsible, he returned seeking revenge. After being defeated by Tiger Mask (Naoto Date), he learned the truth about the organization and Date's noble motives, prompting his defection and transformation into a heroic wrestler.

Years later in *Tiger Mask W*, he appears as an elderly motorcycle shop owner running Takaoka Motors. A permanent leg injury from an unspecified accident requires him to use a forearm crutch. He remains the guardian of Naoto Date's legacy, preserving a secret training facility. When the Tiger's Den resurfaces under the Global Wrestling Monopoly (GWM), he recruits Naoto Azuma—a displaced wrestler from the destroyed Zipangu Pro-Wrestling team—to become the new Tiger Mask. He rigorously trains Azuma, motivated by Azuma's quest for vengeance and his own determination to dismantle the organization again. Throughout the series, he mentors Azuma while guarding Tiger Mask's secret identity, echoing his role as one of the few privy to Date's dual identity in the original series. His character evolves from a vengeful youth manipulated into villainy, to a reformed wrestler embodying nobility, and finally into a determined mentor upholding the heroic spirit he once fought alongside.