After finishing filming a TV mystery mini-drama, Ryuuguu Komachi and Ritsuko return to 765 Production studios for a break with Mami and the Producer returning as well. Iori decides to treat everyone to some special puddings she bought earlier, but finds out the puddings are gone from the refrigerator. Suspecting the other idols as the culprits, Ami and Mami decide to solve the mystery by playing detectives.