Kitsutsuki Tanteidokoro

Adaptation of Kei Ii's mystery novel.

The story is set in 1909 during Japan's Meiji era, and centers on fictional versions of real-life poet Takuboku Ishikawa and real-life linguist Kyousuke Kindaichi, who were acquaintances in real life. Takuboku runs a private detective agency to support his family. Both begin to investigate a case of supposed ghost appearances at the Asakusa Junikai building, also known as the Ryounkai.

(Source: Anime News Network)