Sanshirou Tsuwabuki is an ex-baseball pro who joined the crew of the Space Dragon just when his sports career was leading him to success with a major debut in the Japanese national league as the new pitcher of the Red Sun team.

Japanese baseball had great expectations from his great talent, but Sanshiro was stopped by the Black Birds that Darius sent on Earth to kill him. He was totally unaware of being one of those humans whose superior powers could interfere with Darius’ invasion of the Earth: to kill him without compromising the secrecy of their plans, the Black Birds staged a game accident that cost Sanshiro a fracture at his left wrist, whose consequences forced him to retire from baseball. After that, he survived other two ambushes of Darius’ killers and finally understood the terrible threat that Earth and mankind were facing, so he accepted Prof. Daimonji’s proposal to become the new pilot of the Gaiking, thus completing the crew of the Space Dragon.

Sanshiro lived this dramatic change in his life traumatically: his will couldn’t make up for what the accident did, then he had to face the new challenge of fighting for Earth’s survival with no choice, unlike what happened to his new fellow companions on the Space Dragon. In spite of all this, Sanshiro will not spare himself at all when doing his duty of protecting the Earth with the Gaiking, though his past life never prepared him for a mission like fighting the monsters of the Black Horror Army. Sanshiro will rule on the battlefield and win with the same valour that could have made him a baseball champion, but even the supreme task of Earth’s survival will not make Sanshiro forget his identity as a man with other affections in peace time, that will remain his strongest desire until when he gives them up after realizing that Darius’ war stole him the time of his life.