TV-Series
Description
Koutarou Kirigakure is a fourth-grade student at Aozora Elementary and heir to a ninja dojo with over 400 years of family tradition. He trains under his father, Toubei Kirigakure, though he often skips lessons. His mother, Yayoi, serves as principal of the family-operated Aozora Kindergarten, while his older sister Kasumi is a junior high ace on the badminton team. After the dark wizard Yaminorius III transforms Toubei into a dog named Gonzales, the Kirigakure home conceals a secret ninja training chamber beneath the doghouse.

As a core member of the Miracle Ninja Ganbar Team, Koutarou transforms into Yellow Ganbar using the Ganbar Bracelet and the command "Flushing!". His Ganbare Suit provides super-speed, which he sometimes uses for pranks, reinforcing his reputation as a juvenile delinquent disliked across Aozora City. He pilots the tiger-themed Ganbar Bike motorcycle and the Go-Tiger mecha, which forms the core of the combined robot Ganbaruger. Later, he becomes the primary pilot for Ganbaruger and its enhanced form, Great Ganbaruger, created by combining with the auxiliary mechas Revolger and Gekiryuger. A curse by Yaminorius III threatens to turn him into a dog if his secret identity is exposed, mirroring his father's fate.

Koutarou displays a cheerful, impulsive, and mischievous nature, frequently playing tricks that spark conflicts with residents like childhood friend Chinatsu Yuuki, a school newspaper photographer. Despite their constant quarrels, Chinatsu develops admiration for his Yellow Ganbar persona after he rescues her. He possesses a strong fondness for banana daifuku and a distinct aversion to wasabi pickles. His leadership in the Ganbar Team emphasizes bold actions and immediate results over long-term strategy.

Throughout the series, Koutarou matures battling the Demon World. He confronts personal trials, including his father's extended canine state and his sister Kasumi's temporary corruption into the evil wizard Kasumirius by Yaminorius's magic, reversed after her defeat by Ganbaruger. During the final battle against the Three Great Demon Kings, he forms an unexpected alliance with Yaminorius, who opposes the demons' plan to destroy Earth. Their cooperation leads to the demons' defeat, after which Yaminorius departs. Koutarou maintains his secret identity until a non-appearance cameo in the successor series, *Nekketsu Saikyo Go-Saurer*. His journey balances his prankster tendencies with an evolving sense of duty as Earth's protector.