Rabi, a Long-Eared magic user from Rabiluna on the moon, possesses distinctive features: light skin, messy long blonde hair, and rabbit-like ears usually hidden beneath a white headband. An X-shaped scar marks his cheek. His attire includes a light blue T-shirt with dark blue trim, matching pants, thigh-high dark blue boots, a white sash draped over one shoulder, and white fingerless gloves.

Years orphaned without family or friends forged Rabi into a rude, self-centered, and deeply distrustful individual. This isolation led to a strong preference for solitude and reluctance to form connections, stemming from his unknown lineage.

Chosen as one of three "Madou Warriors," Rabi pilots water-elemental giant robots to fight the antagonistic Jado race threatening his homeland, serving as the Warrior of Water. During this conflict, he forms reluctant alliances with fellow warriors Daichi and Gus, often striving to outperform Daichi.

The Rabiluna arc's culmination reveals Rabi's true identity as Marius von Ramas, grandson of V-Ramas—one of the Long-Eared Tribe's three Grandmages—placing him within the tribe's leadership lineage. The television special "Non-Stop Rabi" depicts his climactic battle against the Jado, where he undergoes a physical transformation to restore his true form.

In novel adaptations, Rabi is a half-breed Long-Eared. His father bestowed magic potential, while his Earthling mother contributed human ancestry. This mixed heritage grants him superior magical abilities compared to full-blooded Long-Eared individuals.