Princess Mirenjo is the princess of Scappola and the primary antagonist leader in the series. She commands a villainous group, the "Mirenjo Gang" (an unofficial name from supplemental materials), comprising mechanic Julie Kokematsu, guard Alan Sukadon, her younger brother Prince Komaro, and Baron Donfanfan.

Mirenjo possesses a strong aversion to defeat, frequently declaring "Mirenjo-hime hates losing." She addresses her subordinates with abbreviated nicknames: "Koke" for Julie Kokematsu and "Suka" for Alan Sukadon. Her distinct speech patterns include using the first-person pronoun "warawa" and the sentence-ending phrase "zo yo." Within the Time Bokan franchise, she embodies the "beautiful but tough female boss" archetype of the recurring "Three Villains" trope, though her male cohorts feature unconventional designs.

Her core mission drives the narrative: pursuing the mythical Firebird (Cosmo Peacock) across diverse historical and fictional settings—including Ancient Egypt, Atlantis, and Edo-period Japan—to secure the throne of the Kingdom of Calendar for her brother Komaro. Their episodic schemes typically end in comedic failure. Specific episodes highlight her traits, such as "Mirenjo's Splendid Transformation" (episode 21), featuring a bathing scene consistent with the franchise's fanservice tendencies toward villainesses.

Prince Komaro is explicitly identified as her younger brother, and both serve the ambitions of the Sukapura Dynasty. No other familial relationships or personal backstory details are provided.

Regarding appearances beyond the original television series, no concrete information confirms her inclusion in OVAs, films, or spin-offs. A gag scene in episode 40 features previous Time Bokan characters as audience members. The Royal Revival OVA focuses on other villain trios, excluding Mirenjo's group.