Maria Grace Fleed is the younger sister of Duke Fleed, crown prince of the destroyed planet Fleed. Separated during the Vegan Empire's attack, Maria escaped to Earth in an escape pod with a loyal royal servant. This servant assumed the role of her grandfather, raising her while suppressing her memories of Fleed to ensure a peaceful life. Her guardian perished during a crossfire between Grendizer and a Vegan Saucer Beast, revealing her true heritage with his dying breath. Blaming Grendizer's pilot for this loss and believing the robot stolen by Vegan forces, Maria swore vengeance. Initially hot-tempered and revenge-driven, Maria used a stolen Vegan spacecraft to relentlessly attack Grendizer. A direct confrontation led Duke to recognize a shared family locket, triggering Maria's suppressed memories and revealing their sibling relationship. This reunion shifted her focus from vengeance against Duke to joining his fight against the Vegan Empire. Her personality evolved into a more sociable demeanor, though she retained assertiveness. She developed romantic feelings for Koji Kabuto, frequently arguing with him, though these feelings remained unreciprocated. She formed a friendship with Hikaru Makiba, unaware of Hikaru's affections for Duke. Maria demonstrated significant piloting capabilities, skillfully operating the stolen Vegan craft, an off-road motorcycle, and later the Drill Spazer combat support vehicle. Her piloting skills were noted as being on par with Koji and Hikaru. She possessed limited precognitive abilities, sensing impending enemy attacks, and wielded a Vegan blaster and saber effectively in combat. After joining Duke's team, Maria became a core member, providing crucial support in the Drill Spazer during battles against Vegan forces starting consistently from episode 49 onward. She participated in the final assault destroying the Vegan mothership and Emperor Vega. Following the Vegan Empire's defeat, Maria departed Earth alongside Duke to aid in Fleed's reconstruction. In the manga adaptation by Gosaku Ota, Maria shared a close childhood bond with Duke despite often being raised separately. Her memories were similarly suppressed upon arriving on Earth. Her initial rage upon learning her heritage was more pronounced, extending to perceived enemies. Her attraction to Koji caused friction with Duke and Sayaka Yumi. The "Grendizer Giga" manga reimagining replaced much of the original cast, offering a divergent interpretation.