College student Kyohei Arisugawa lives a thoroughly unremarkable life. His one and only claim to fame is being the cousin of Ren Arisugawa, Japan's hottest young male celebrity, a charismatic idol admired by millions. Kyohei has not seen his famous relative in years, so he is shocked when Ren suddenly shows up unannounced at his small, rundown apartment looking for a place to crash.

The late-night reunion takes a bizarre turn when Kyohei accidentally walks in on Ren while he is changing. In that instant, Kyohei discovers a secret that could shatter the entertainment industry: Ren Arisugawa is actually a girl. The cool, confident, and handsome persona presented to the public is a complete fabrication. In reality, Ren is a young woman who has been disguising herself as a man to achieve stardom, and off-camera, she is surprisingly adorable and self-conscious about her femininity.

Panicked that her true identity will be exposed, Ren begs Kyohei for his silence. He soon finds himself trapped in a high-stakes situation, forced to become Ren's personal assistant to help maintain the elaborate deception. As Kyohei is pulled deeper into the glamorous yet treacherous world of show business, he must navigate a series of scandals and eccentric personalities while keeping Ren's biggest secret safe from ravenous fans and ruthless media.

The main cast includes the two cousins at the center of this secret. Ren is the popular male idol whose hidden vulnerability contrasts sharply with her stage persona. Kyohei is an insensitive and somewhat irresponsible university student, though he possesses a kind heart that ultimately compels him to protect his cousin. Supporting them is Satsuki Yoshioka, Ren's longtime manager who treats her like a younger sister but has a notoriously bad drinking habit. The story also involves Momoka Hiiragi and Haruna Miyashita, two members of a popular idol duo. Momoka is genuinely excited to co-star in a drama with Ren, while the cool and composed Haruna always looks out for her. Finally, Hina Sugisaki is a free-spirited female friend with whom Kyohei has a complicated history.

The narrative unfolds across two main settings: Kyohei's modest apartment, which becomes a safe house for Ren to drop her masculine act, and the dazzling but demanding world of television studios and promotional events. Notable narrative arcs include Kyohei struggling with his new role as Ren's assistant as he tries to keep her identity a secret in public. Their forced proximity leads to a complicated and forbidden relationship that blurs the lines between familial obligation and romantic attraction. Additional complications arise when Ren begins co-starring in a drama with the idol duo, introducing new characters who get dangerously close to discovering the truth and who form their own entanglements with Kyohei.