A wandering youth and aspiring boxer, Kōtarō returned to Japan after extensive travels. His strong sense of justice drove him to intervene during a monster attack by Oil Drinker and Astromons, sustaining fatal injuries. The Ultra Brothers transported his body to Nebula M78’s Land of Light, where Mother of Ultra merged his life force with Ultraman Taro, reviving him as a merged entity. This allowed Kōtarō to transform into Taro using the Ultra Badge—a device given by Mother of Ultra in her human guise as the "Lady in Green," who resembled his deceased mother. **Ultraman Taro** Prior to the merger, Ultraman Taro existed as a distinct Ultra warrior: the biological son of Father of Ultra and Mother of Ultra, native to the Land of Light. Trained rigorously under his father, he interacted with peers like Tregear. Sent to Earth to combat threats like Enmargo, he joined the Ultra Brothers as their sixth member after proving valor in battles such as defeating Grand King. His pre-merger history established him as separate from Kōtarō before their fates intertwined. **ZAT and Human Growth** As a ZAT (Zariba of All Territory) member, Kōtarō defended Earth from kaiju and aliens. Initial recklessness matured through experiences, particularly his bond with Captain Shiratori’s children, Kenichi and Saori, emphasizing themes of familial responsibility. After Captain Shiratori’s death during Samekujira’s attack, Kōtarō’s guilt over failing to protect him catalyzed his decision to relinquish Ultra powers. In the finale, he returned the Ultra Badge to Mother of Ultra, severing his Taro connection to live solely as a human. He then defeated Alien Valky using ingenuity and environmental tactics, proving growth without Ultra abilities. **Taro’s Capabilities** Ultraman Taro wielded superhuman strength, heat resistance, and flight. His primary weapon, the Strium Beam, unleashed multicolored energy from a T-shaped stance with immense destructive power. Resurrected after dying against Birdon, he received the King Bracelet from Mother of Ultra, enabling auxiliary functions like generating restraints or tools. His extreme technique, Ultra Dynamite, involved self-detonation to obliterate opponents but severely depleted his energy. **Relationship and Legacy** Kōtarō and Taro’s bond was a fusion, not symbiotic possession. Mother of Ultra treated Kōtarō as her son, and Taro referred to Ultra Brothers as siblings—extending to biological ties: Father of Ultra as his father and Ultraman Ace as his adoptive brother. Post-Earth, Taro fathered Ultraman Taiga, mentored warriors like Ultraman Mebius at the Ultra Coliseum, and continued his legacy through cross-dimensional battles against threats like Inpelaizer, Alien Empera, and Yapool. **Alternate Depictions** Non-canonical media diverged: Ken Ishikawa’s manga portrayed Kōtarō as Kotaro Azuma, granted Taro’s powers by Mother of Ultra after a near-fatal encounter without a pre-existing Ultra identity. The *Princess Comet: Kumiko Ohba* crossover showed him as an adult aiding an alien youth, violating cosmic laws and departing Earth permanently. **Post-Series Ambiguity** Kōtarō lived as a human post-series, while Taro persisted separately in the Land of Light. This duality surfaced in later series like *Ultraman Leo*, where Taro’s absence during an Ultra Brothers mission implied Kōtarō’s human life took precedence. The 1984 film *Ultraman Story* retroactively emphasized Taro’s Nebula M78 upbringing, sidelining Kōtarō—shifting portrayals to Hiroya Ishimaru voicing Taro exclusively.