It's likely a light novel set in Kyoto. The 'Teramachi Sanjou' might be the location within Kyoto where the story unfolds. And 'Holmes' in the title could imply that the story has elements related to mystery or deduction, similar to the famous Sherlock Holmes stories.
Well, from what the title suggests, it's probably centered around the area of Kyoto called Teramachi Sanjou. There could be a character in the story who is like Holmes, perhaps a very intelligent and observant person. Maybe there are various mysteries in this area of Kyoto that the main character, like Holmes, tries to solve. It might also involve the local culture and scenery of Kyoto, which could add an interesting backdrop to the mystery - solving elements.