Kurumi Tokisaki is a college student with a dark past who now works as a detective specializing in crimes involving magical artifacts known as Artifacts. These are objects imbued with powers that surpass human understanding. After dozens of these powerful items are stolen, a wave of supernatural crimes begins spreading across Tengu City. A magic bullet fired from an impossible angle, a living doll mixed up in a series of mysterious comas, an absurdly expensive meal said to restore ones youth, and a doppelganger spotted at an all-girls school following an attempted suicide. These Artifacts make the impossible possible, and Kurumi, known as the magic detective, is the only one who can solve these cases.

Alongside her companion Matsurika, Kurumi works to unmask the dastardly thief behind the Artifact thefts and retrieve the stolen items. As each incident is resolved, however, the identity of the mysterious perpetrator only becomes less clear. The narrative follows Kurumi as she tackles multiple standalone cases while pursuing the overarching mystery of the Artifact thief.

The story is set in Tengu City several years after the events of the main Date A Live series. After her powers as a Spirit were sealed by Shido Itsuka, Kurumi enrolled at Saito University and established the Tokisaki Detective Agency. She now lives alongside the other former Spirits who attend the same university, including Tohka Yatogami and Origami Tobiichi, with whom she maintains friendly relationships and occasionally shares meals.

Notable cases include the Dollhouse incident, where Kurumi investigates a series of comas linked to an online group and confronts a hospitalized child named Megumi Katashiro who uses an Artifact to transfer souls into dolls. Another case involves a restaurant serving Rejuvenating Cuisine, where Kurumi discovers that chef Hatoko Mikuriya uses an Artifact called Vampir as a kitchen knife to steal vitality from customers, making them feel artificially youthful while burning away their lifespan. A third case takes Kurumi to St. Adelina Girls School to investigate a students mysterious wounds and reported doppelganger sighting. Throughout these investigations, Kurumi applies her sharp intellect and experience from her past as the Worst Spirit to solve crimes that ordinary detectives cannot explain.