Rei Asuka is a woman cloaked in mystery, wielding unexplained psychic powers and bound to the ancient protector Raideen. Initially cloaked in the guise of a nun, she surfaces to issue cryptic warnings about threats posed by the Demon Empire, later revealing herself as a pivotal ally. She commands a support vehicle alongside Riki Jinjuki, directly aiding Raideen in combat.

Her past entwined with a motorcycle gang and a fraught romance with Jagger—a delinquent harboring animosity toward Akira Hibiki—culminates in a hostage crisis. The confrontation dissolves through her negotiation, though Jagger perishes shortly after. Rei mourns silently, scattering torn flower petals as a testament to lingering sorrow.

Crimson-haired and aloof, Rei contrasts sharply with her peers. Her telepathic bond with Raideen amplifies its power, and she spearheads reconnaissance missions, including a Tibetan expedition to uncover Princess Lemuria, heir to the Mu Empire’s legacy. During this quest, she is ambushed by a Fossil Beast and vanishes without trace.

The narrative offers no resolution to her disappearance, nor do other characters acknowledge her absence. Subsequent media offers no elaboration on her fate, cementing her arc as an enduring enigma within the series’ lore.