Fuu Nonoyama is an energetic elementary schooler looking forward to summer vacation, while her older sister Rui is a studious junior high student who has grown distant from her. Their strained relationship is upended when Fuu stumbles upon a mysterious spaceship that only she can see, and is granted the power to transform into a magical girl idol. At the same time, Rui receives the same power from a talking cat-like spirit. The catch: their magic lasts only one year, and they must never reveal its existence to anyone.

Independently adopting the stage names CompatoLilly (Fuu) and MashuLulu (Rui), both sisters are scouted by the talent agency Production Once More and begin their careers as idols, completely unaware of each other’s secret identities. As they balance school, family, and their new performing lives, their paths cross increasingly often—on live TV, at a chaotic quiz show where Fuu’s playful magic goes awry, and during a summer training camp at a beach house haunted by a teddy‑bear‑like creature. A haunted house trap forces the two to unknowingly cooperate using their powers, slowly rebuilding the closeness they once shared.

The first twelve episodes follow the sisters’ rise as an idol duo, the complications of keeping magic hidden, and the growing bond between them as they face both mundane challenges and supernatural mishaps. A second part, set to continue the story, picks up after the one‑year time limit begins to loom over their magical lives.