Koutaro Taiga is the loud, proud, and quite energetic president of the Space Development Corporation and chief of the Gutsy Geoid (later Galaxy) Guard. It is Taiga's job to oversee GGG's mission, and to approve the use of necessary procedures (Final Fusion, Symmetrical Docking) as well as more crucial and untested equipment (Goldion Hammer, Goldion Crusher, Projectile X and so on).
As Chief, his job is also to report to the GGG's overseeing body (the Japanese Diet, then later the U.N) and also request more budget allocations as well as argue GGG's case and purpose on occasion.
While GGG was based in Japan, his approval essentially represented the Prime Minister's approval, and in space, it represented the approval of the U.N. Secretary General (according to the box containing the Gold Key).
He is apparently married and has two daughters(though it is not mentioned in the series or FINAL), and enjoys playing golf when not on duty as President or Chief. As such, he is handy with a golf club (the "Titanium-Head Driver" and later the "Taiga Wood").
