Chao Lee is a 17-year-old member of the F-99 unit within the DICE organization, operating in the Sarbylion galaxy. An orphan shaped by wartime tragedy where his family fell victim to conflict—a background shared by all F-99 members—he fulfills dual critical roles as both pilot and navigator of Fortress F-99. His calm and supportive nature makes him a stabilizing force within the team; he readily offers advice to distressed teammates and voices dissent to his captain when necessary.

Chao cares for a pet named Moke, adopted after poachers killed its parents. Moke exclusively vocalizes Chao's name, highlighting their deep bond. Unlike most F-99 members, Chao does not routinely operate a personal Dinobreaker for standard missions. Instead, he commands the unique Tortoise Fortress—the physical embodiment of Fortress F-99—which transforms into a combat-ready form to confront giant threats during critical situations.

His responsibilities place him at the heart of mission-critical scenarios, from navigating hazardous environments like plasma blizzards to participating in large-scale operations, though these actions remain tied to broader team activities. No significant character evolution beyond his established role appears in later seasons or other official media extensions.