There is an antique shop in the Teramachi Sanjou shopping area in Kyoto. When there were strange cases, the son of the shop owner, Kiyotaka Yagashira was able to solve them well. Because of his abilities, he was nicknamed "Holmes at Teramachi Sanjou". Together with a high school girl, Aoi Mashiro who is a new shop worker, they solved various cases brought by clients.