Discovered adrift in space within an emergency pod during Trava and Shinkai's survey mission to Planet Fable, Mikuru is rescued when their Speedmaster mecha retrieves the vessel. She awakens with complete amnesia, retaining no memories of her past or identity—only the name "Mikuru," derived from text on her shirt. A medical examination reveals a scar and confirms deliberate memory erasure, a procedure Trava theorizes wealthy individuals might undergo to escape wartime trauma. Her background remains obscured, though the advanced pod and erasure imply a privileged or significant history.

After rescue, she accompanies Trava and Shinkai to Planet Fable. En route, she learns of their objective: competing in the Fist Planet tournament, a high-stakes mecha battle for prize money to cover debts and entry fees. Mikuru exhibits curiosity about their world, inquiring about sentient "Thinking Weapons" and the function of Powers like the Speedmaster.

A preview for the unproduced *Episode 2* sequel depicts her evolution. She reappears as a princess alongside Reiter, her cybernetically enhanced giant guardian. The pair confront Trava and Shinkai at the Fist Planet arena, where Mikuru challenges Shinkai in a mechanics' competition while Reiter battles Trava. This signals her shift from helplessness to assertiveness and hints at unresolved rivalry between her faction and her former rescuers.