Miki is a core member of the Blue Sky orphanage group alongside Takeshi, Goro, and Matsuo. When Takeshi discovers his extraterrestrial heritage as prince of planet Apolon and gains control over UFO saucers, Miki becomes directly involved in subsequent operations. She is recruited as a pilot for robotic components at an undersea base.

Miki operates the Trangur (also called Trangu), the trunk section of a combined robotic entity. She participates in transformation sequences activated by the vocal command "U! F! O!", which triggers a magical uniform change for all pilots. Her role requires coordination with Goro (pilot of the Header/Head unit) and Matsuo (pilot of the Legger/Leg unit) to execute the combination sequence forming the complete Dai Apolon robot. This combined form functions as cybernetic armor for Takeshi after his "body fusion" process, activated by the internal "Key Energy" device enabling his growth to giant size.

In the 1986 English-dubbed compilation film adaptation—which re-edited series episodes, relocated the setting to California, and Americanized character names—Miki's name was changed to "Mickey". Her fundamental role as Trangur pilot remained consistent within this adapted narrative structure.