Full Name: Soutarou Ushigome
Ranger Designation: GaoBlack
Title: Iron Bison
Weapons: Beast King Sword, Bison Axe
Gear: G-Phone
Special Attacks: Iron Broken, Iron Twister (With GaoBlue)
Power Animals: Gao Bison, Gao Rhino, Gao Majiro
Soutarou was twenty-two years old when the saga began. He was chosen as a Gaoranger about a month before Kakeru. He aspired to become a grand champion sumo wrestler, but a knee injury forced him to retire from his wrestling career. Afterwards, he worked as an assistant at Flower Garden Casablanca with his crush, Shi-chan. Though he is the strongest out of the Gaorangers, he is a very gentle soul with a fear of heights and a weakness for women. When Shi-Chan was invaded by the Eyeglasses Org, he was forced to give up his Bison Jewel and even asked Shi-chan her hand in marriage. Unfortunately, she wasn't really Shimada. Shimada eventually was released herself from the Org and Soutarou returned to the Gaoranger. After the final battle, he returned his G-Phone and jacket to Tetomu. He and Shi-chan worked together on a ranch although he and Kai initially planned to run a Chanko shop together to "dominate the world.".

Later in 'Hurricanger vs Gaoranger', he was kidnapped with his former team members by Tsuetsue and Yabaiba and their G-Phones were given to the Jakanja. He was impersonated by Manmaruba of the Jakanja. They escaped with the help of the Hurricanger, Goraijer and Shurikenger and defeated Tsuetsue and Yabaiba and the Jakanja.