Reiki Beni (Tomonori Hirose), the second head of the Beni Detective Agency, along with his partner Shoji Ai (Gentoku Aoki), underground idol Saori (Asuka Kishi), and Yayoi (Reiko Yakima), Reiji's grandmother and the owner of the detective agency, spend their days searching for pets and investigating cheating at the detective agency they inherited from their grandfather.

Even after solving the previous case, the Beni Detective Agency's daily life continues unchanged. Then one day, a young man comes to the office who admires Reiji and wants to work there. His name is Yusuke Yanagisawa. The first request that the two of them make is to investigate the disappearance of a sword used in a play. The client is the leader of a troupe of traveling entertainers.