In a realm where doppelgängers lurk, entrusted with the task of eliminating their human counterparts, a mischievous devil named Joon finds himself in a moment of distraction, resulting in the creation of Doh Seong-ah. Intended to replace Lee Woo-yeol, Seong-ah unexpectedly takes on the appearance of Joon’s beloved idol! Undeterred by this twist of fate, Seong-ah ventures into the human world to fulfill his mission. However, the formidable and terrifying nature of Woo-yeol proves to be a challenge beyond Seong-ah’s expectations… Can he overcome these obstacles and eliminate Woo-yeol as planned? Or will the world be big enough for both of them to coexist?