Rina Takamiya arrives at St. Paulia's Academy as a transfer student, leveraging her status as the mayor’s niece to join the Saint Tail investigation. Driven by a fierce ambition to become a police officer, she fixates on apprehending Saint Tail, viewing the phantom thief as both a professional rival and an obstacle to winning the affection of Daiki Asuka (Asuka Jr.), her classmate entangled in the chase.

She stands slightly taller than her peers, including Asuka Jr.—until he outgrows her—with short dirty-blonde hair, reddish-brown eyes, and the academy’s standard uniform. During investigations, she dons a teal jumpsuit, channeling her stubborn, headstrong nature into physical confrontations and unorthodox tactics like tear gas deployment, frequently clashing with Asuka Jr.’s strategic approach.

Convinced Meimi Haneoka is Saint Tail, Rina relentlessly confronts her, wagering with Asuka Jr. that proving Meimi’s guilt would secure her a romantic relationship with him, while failure would end her accusations. The bet collapses when Saint Tail deceives her with an adult male decoy, forcing Rina to abandon her theory.

Later, threatened by Asuka Jr.’s reluctance to arrest Saint Tail, she schemes to remove him from the case, only to relent after he passes the mayor’s test of resolve. Gradually accepting his bond with Meimi, she supports their relationship. Eight years post-academy, she achieves her police career goal, still oblivious to Saint Tail’s true identity.

Born May 19 with blood type B, Rina’s blunt assertiveness contrasts Meimi’s nimble grace. Her journey transitions from rivalry-fueled obsession to embracing both personal growth and professional purpose, cementing her evolution beyond initial antagonism.