Prima Doll: Kouto Tantei is the third volume of the kinetic novel series based on the multimedia project Prima Doll, which is a sequel to the anime series.

A few months after the runaway incident of Haizakura, when she is in a long sleep for maintenance - it is the autonomous dolls Gekka and Retzel who are secretly scrambling to deal with the still frequent incidents of dolls running amok. They run around the Imperial Capital at night to save the dolls from their sad fate.