LOONA TV Prequel (이달의 소녀 탐정, Idalui Sonyeo Tamjeong, Girl of the Month Detective) is a spin-off series of LOONA TV. It was introduced on December 30, 2016.
In this series, a hash sign in the title determines which girl, in order of debut, is featured in the episode; for example, #a is HeeJin, #f is Kim Lip, while #k is Go Won.
These episodes were filmed before the girls were selected as official members, so they were sometimes blurred to prevent their identity from being revealed. The episodes also included blurred trainees who were not chosen as members of LOONA.