Aira Mu reigns as queen of Mu, an ancient kingdom within a parallel dimension. Daughter of King Muraji, she governs a realm besieged by invasions from the Dragonia Empire under Emperor Dorado and Prince Eldo. A prophecy in Mu predicts the chosen hero Yamato will awaken the stone statue God Mazinger to protect the kingdom.

Aira wields the power to project her thoughts and voice across dimensions, summoning Yamato Hino from Earth when Mu faces attack. After Yamato awakens God Mazinger, she integrates him into the royal court as Mu's champion. She demonstrates strategic leadership during the conflict, coordinating defenses against the empire's dinosaur armies and Warrior Beasts. Aira pilots the Goddess Mazinger, a female counterpart to God Mazinger, though her piloting skill is less proficient than allies like Jun Hono.

Within the manga continuity, Prince Eldo attempts to capture Aira following his deployment of forbidden weapons against Mu's forces. In a separate storyline, Jun Hono arrives in Mu in response to Aira's prayers. Aira provides her shelter, forming a close friendship, and volunteers to pilot Goddess Mazinger to protect Jun. She nearly faces defeat until Jun intervenes using the powered-up Venus A, the Queen of Gold, to vanquish the Emperor of Darkness.

Mu later falls to destruction by the Dragonsaurus. Aira is presumed dead, yet her spiritual presence endures. She contacts Jun through dreams, warning of the Dragonsaurus in the modern era and revealing the method to defeat it by targeting the Sacred Treasure within its body. This guidance enables Jun and the MA robots to destroy the monster.

Aira possesses long black hair and typically wears a red dress adorned with Mu symbols, crowned as queen. When piloting Goddess Mazinger, she dons a helmet resembling the mecha's head.