The story follows two orphaned sisters, Kisugi Nami and Mina. Nami possesses the talent to mimic voices and on their uncle's suggestion, voices a character in a game called "Female Detective Omega," using "Minami" as an alias.

Owing to Nami's shyness, it is Mina who appears as Minami on the Omega live show and unfortunately, falls off the stage. Nami suspects another voice actor Tojo Kasune—who kept staring at Mina during rehearsal— of having pushed Mina, but he denies it and instead accuses Mina of not being the real Minami and fingers Nami as the true Detective Omega.