Rieko serves as Akira’s guardian, the son of Professor Gill, masquerading as a human caretaker while concealing her enigmatic ties to Gill’s history. Tasked with shielding Akira from entities like SHADOW—which aims to extract encoded blueprints hidden within the boy—her fabricated humanity unravels during a clash with Hakaider, an antagonist housing Gill’s brain. He exposes her true nature as a mechanical construct engineered by Gill, embedded with another’s memories to secure her loyalty. Destroyed by Hakaider, her demise precipitates a pivotal shift in allegiances, spurring Bijinder, a SHADOW-affiliated android, to abandon her faction and aid the protagonists. Before her destruction, Rieko directs the group to a dam sanctuary, navigating threats with strategic resolve. Her artificiality fuels friction with allies like Rei (Kikaider 00), whose skepticism underscores tensions between organic and synthetic beings.

In the live-action tokusatsu iteration, Rieko similarly safeguards Akira as a wholly human protector. Here, she sacrifices her life during a climactic battle to ensure his survival, diverging from her android counterpart’s fate in the animated continuity. Both versions anchor narratives examining guardianship, constructed identity, and the ethical ramifications of artificial life.