Captain Gideon holds the rank of senior officer in the Earth Defense Force. In 2201, he commands the experimental warship *Andromeda*, spearheading defense against the initial Gatlantis invasion near Saturn. During the broader conflict with the White Comet Empire, he initially commands a different vessel in the outer solar system. After this ship suffers catastrophic damage and his patrol fleet is annihilated by Comet Empire forces, the *Yamato* rescues him. Gideon subsequently takes command of the *Yamato* and is officially appointed its captain by Earth Defense Force leadership.

When the Comet Empire assaults Earth, Gideon leads the Defense Force fleet from the *Andromeda*, successfully repelling the first assault wave. However, overwhelming enemy forces later destroy the fleet in subsequent battles. Gideon remains aboard the *Yamato* as it continues the fight against the Comet Empire. He is killed in action against Gatlantis forces while serving as the *Yamato*'s captain.

Prior to the full-scale invasion, Gideon pilots the *Andromeda* on an approach vector that nearly causes a collision with the *Yamato* due to communication failures. Neither vessel alters course, demonstrating his uncompromising command demeanor. His name derives from the historical figure Hijikata Toshizo, deputy leader of the Shinsengumi.