Corporal Koyo was a commando, specifically a male Human, who fought in the Galactic Civil War. He was part of the Imperial Army's Special Ops Ghost Battalion, more precisely, the Second Platoon of B Company. During the year 1 BBY, Koyo took part in the Subjugation of Sulon. His squad, led by First Lieutenant Brazack, forcibly entered the Katarn homestead with the mission of capturing Morgan Katarn. Koyo was the one who breached the entrance, and he then, along with Santo, forced open the workshop doors, which activated the home droid WeeGee's defense protocols. Because Morgan was not present at the Katarn homestead at that time, he observed the invasion from a secure distance. The team went back to their base without having accomplished their objective.