Go Mi-Nyu, a sweet and naive girl training to become a nun, is suddenly pulled into the glamorous chaos of the K-pop world when she agrees to impersonate her twin brother, Go Mi-Nam. Mi-Nam, who has just been accepted into the hit idol group A.N.JELL, must recover from botched surgery in the U.S. Hoping to help him reunite with their long-lost mother, Mi-Nyu disguises herself as a boy and steps into his place. Living under the same roof as the other members—prickly perfectionist Hwang Tae-Kyung, kind-hearted Kang Shin-Woo, and playful Jeremy—Mi-Nyu’s secret becomes harder to protect as unexpected emotions begin to surface. While Shin-Woo quietly protects her identity, Tae-Kyung eventually uncovers the truth and, despite his cold nature, begins to fall for Mi-Nyu. But things grow more complicated when jealous pop star Yoo Hee-Yi blackmails Tae-Kyung into a fake relationship, forcing him to suppress his growing feelings. As love triangles intensify and secrets unravel, Mi-Nyu must decide how long she can keep pretending and what it might cost when the truth finally comes to light.