Windam stands as one of three ancient Rune Gods, legendary guardians of Cephiro embodying the element of wind alongside wisdom and the past. It manifests physically as a giant green bird possessing four wings, its shrine housed within a floating crystal mountain. This entity shares an intrinsic bond with Fuu Hououji, the Magic Knight of Wind, who becomes its pilot upon its revival.

Windam's abilities focus on wind-based magic, primarily defensive and supportive. Its signature attacks are the powerful gust "Emerald Typhoon" and the anime-exclusive "Emerald Cyclone," which unleashes simultaneous blade-like wind gusts. As an extension of Fuu's power, Windam also enables healing spells like "Winds of Healing" and immobilization techniques such as "Winds of Admonishment."

The circumstances of Windam's revival and bonding with Fuu differ across media. In the anime, Fuu awakens Windam by proving her selflessness during a test at the Temple of Sky, choosing to save Ferio over claiming the god's power. The manga depicts a different trial where Fuu confronts her own doubts and insecurities to earn its allegiance. This partnership strengthens during Cephiro's crisis in the second arc as Windam aids in defense against invading nations.

Windam participates in combined assaults with the other Rune Gods, Rayearth (Fire) and Celes (Water), including the unified energy blast "Spiral Flash" and their most potent coordinated strike, the sword-based "Flash Sword." Within the OVA narrative, Windam opposes Ferio during Cephiro's invasion of Earth, reflecting an alternate storyline where Fuu battles former allies under different motivations. The name Windam derives etymologically from the Toyota Windom.