Kengo Tachibana is a serious twenty-two year-old student who takes his role as a B-Fighter seriously. Even when on vacation, thought only about getting back to fighting the good fight. He originally had no respect for Kouhei he had wanted to be B-Fighter Kabuto, and couldn't believe that someone younger than him, a highschool student was chosen. They did eventually became friends. The armor Kengo wears as B-Fighter Kuwaga is modeled after a stag beetle (kuwagata-mushi). His Finish Weapon is the Kuwager Chopper, which he can perform the deadly Gravity Crush attack. At the end of the series, Kuwaga is able to wield the Geist Axe and take control of the giant robot, Kuwaga Titan, which was formerly used by Melzard/Death Scorpion for evil.