General Sadak is Emperor Daibazaal's most capable military leader within the Galra Empire. He spearheads the invasion of the Dark Nebula and oversees the enslavement of its conquered populations. Following Earth's thermonuclear war in 1999, Daibazaal commands Sadak to capture survivors, including five students from the Fuji Space School. When these captives escape Slave Castle and flee to Altea, Sadak receives orders to pursue and recapture them. His mission fails as the escapees activate the sentient robot Golion, resulting in the destruction of a Deathblack Beastman deployed to support Sadak.

Subsequent campaigns against Golion and its pilots yield a series of defeats for Sadak, progressively eroding his standing with Emperor Daibazaal. Sadak employs harsh military measures, including ordering the execution of weak or sick slaves by feeding them to Deathblack Beastmen. His initial arrogance and confidence as Daibazaal's favored commander diminish due to his persistent failures against Golion.

By early 2000, Daibazaal condemns Sadak to death for his accumulated failures. During the execution proceedings, Prince Sincline intervenes upon returning from his conquest of the Great Goering Nebula. Sincline proposes transforming Sadak into a Deathblack Beastman as a final chance to destroy Golion. Daibazaal agrees, sparing Sadak for this purpose. Converted into a biomechanical entity, Sadak accompanies Prince Sincline back to Altea for a decisive confrontation. In the ensuing battle, Golion kills Sadak. His death enables Prince Sincline to assume command of the Galra Empire's military forces.