Episode 21

Double Black (つの黒,) is the 21st episode of Bungo Stray Dogs anime series. It first aired on November 26, 2016.

Synopsis
The leaders of the Agency and the Port Mafia negotiate an alliance. Meanwhile, Dazai and Chūya face off against Lovecraft.

Summary
At the Agency's office, Kunikida berates Dazai for his laziness, before being interrupted by the boss Fukuzawa, who asks if Dazai has proceeded on the plan to have a meeting with the Port Mafia. Kunikida is confused about why Dazai is able to do such a thing and is shocked to learn that Dazai was a former Mafia member. Kouyou delivers the invitation to Mori, who reminisces when he killed the previous boss of the Mafia. During the meeting between the two bosses, they eventually tentatively agree to a temporary ceasefire after a minor skirmish between the bosses.

Dazai is sent to recover Q, with the assistant of Chuuya sent by the Port Mafia. The two wipe out the Guild members protecting Q, with Mori saying that the "Soukoku" has revived for the night. As the two return to the surface, they are attacked by Lovecraft. The two seemingly defeat Lovecraft before he changes into an eldritch monster, causing them to have to use Corruption. The rampaging Chuuya is able to defeat Lovecraft at the cost of injuring his own body, to the shock of John.