Yen Press publishes the manga in English, and it describes the story:
Seven years before the events of Bungo Stray Dogs, a young Osamu Dazai is ordered by Ougai Mori to investigate an ominous rumor―there have been sightings of Mori's deceased predecessor, and the new Mafia boss would very much like for the dead to stay buried. Along the way, Dazai runs into a gravity manipulator named Chuuya Nakahara, leader of the teenage Sheep gang. Together, the two will one day achieve infamy as the fearsome duo Twin Dark, but for now, they'll have to learn to cooperate if they want to get to the bottom of this mystery…
Hoshikawa launched the manga in Kadokawa's Shōnen Ace magazine in September 2022. The manga is based on the spinoff light novel of the same title that shipped in August 2019, and explores the past of the characters Osamu Dazai and Chūya Nakahara. Kadokawa shipped the manga's third volume on March 4.
Kafka Asagiri and Sango Harukawa launched the Bungo Stray Dogs manga in Kadokawa's Young Ace magazine in December 2012, and the series is ongoing. Yen Press is publishing the manga and novel series in English.
The manga's first television anime adaptation aired from April to June 2016, and Crunchyroll streamed the series as it aired in Japan. The anime's second 12-episode series aired from October to December 2016, and Crunchyroll again streamed the series as it aired. Funimation and Crunchyroll released the series on home video with an English dub. The anime's third season premiered in April 2019, and Crunchyroll and Funimation both streamed the season.
The anime's fourth season premiered in Japan on January 4. The season's final episode aired on March 29. Crunchyroll streamed the anime as it aired in Japan, and it is also streaming an English dub.
The anime's fifth season premiered in July 2023, and ended in September 2023.
An anime film titled Bungo Stray Dogs: Dead Apple opened in Japan in March 2018. Crunchyroll began streaming the film in September 2018, and Funimation began streaming the film in June 2019.
Source: Amazon