Meimi Haneoka, a 14-year-old student at St. Paulia’s Academy, balances her ordinary life with her clandestine role as Saint Tail, a vigilante phantom thief. Drawing from her heritage—a stage magician father and a former phantom thief mother—she merges their crafts to orchestrate heists that restore stolen goods or correct injustices, guided by intel from Seira Mimori, her trainee-nun confidante.

As Saint Tail, she dons a magician-themed ensemble with a distinctive ponytail, deploying tools like playing cards, doves, and balloon clusters for escapes and diversions. Her transformation, marked by the incantations “One… Two… Three!” and “It’s showtime,” intertwines theatrical flair with ethical purpose. Though devoid of supernatural powers, her expertise in illusion and agility lets her outwit pursuers, including Asuka Jr., her classmate and detective’s apprentice, whose initial quest to capture her gradually morphs into mutual attraction.

Their dynamic pivots from adversarial rivalry to tentative romance, strained by Meimi’s guilt over concealing her identity and Asuka Jr.’s escalating suspicions. When he confesses his feelings, she grapples with fears of betrayal, a conflict climaxing as rival thief Rosemary exposes her secret and kidnaps him. During the rescue, Asuka Jr. metaphorically “captures” her, releasing her from Saint Tail’s burdens and embracing her true self.

Retiring from thievery, Meimi embraces normality, later marrying Asuka Jr. and symbolically shedding her past via a short haircut. He becomes a private detective, pursuing justice through Seira’s guidance, while her secret remains safeguarded by allies.

Confident yet compassionate, Meimi’s resolve to aid others clashes with insecurities over her dual life, particularly risking her bond with Asuka Jr. Her journey navigates identity, trust, and balancing duty with personal fulfillment, culminating in a life where legacy and love coexist.