Bungou Stray Dogs - Tantei-sha Setsuritsu Hiwa?

Tantei-sha Setsuritsu Hiwa, or The Detective Agency Establishment Untold Story, was written by Kafka Asagiri as a light novel prequel to the main Bungou Stray Dogs series. It was published in Japan to provide essential backstory regarding how the Armed Detective Agency was first formed by Yukichi Fukuzawa and Ranpo Edogawa. By focusing on the initial meeting between the two protagonists, Asagiri deepens the lore of the franchise, shifting the focus from the chaotic battles of the main timeline to the character-driven origins of the organization's moral compass.

The narrative design serves to humanize Fukuzawa, portraying him before he became the stoic leader known to fans, and highlights the formative influence of Ranpo's analytical genius on the agency's founding principles. Sango Harukawa provided the character illustrations that maintain the distinct, sharp aesthetic of the series. The volume was well received by the existing fan base for its ability to bridge the gap between character motivations and the world-building of the greater Bungou Stray Dogs universe, eventually being adapted into an anime format that further cemented its place in the series canon.