Chapter 50

Mutual Destruction, Part 4 (共喰い 其の肆,) is the 50th chapter of the Bungo Stray Dogs manga.

Summary
Mori and Fukuzawa decide to settle the war once and for all and both go to a place that only they know. They both decide to end the war with a duel. Mori summons Elise, the manifestation of his ability, Vita Sexualis.

Several years ago, Fukuzawa was ordered by Sōseki Natsume to protect Mori, then an underground doctor who treated patients from various organizations in his neutral clinic. That night, Mori was captured by a group of illegal immigrants who asked him for intel regarding the Port Mafia's armory location. Despite the various men assigned to guard outside, Fukuzawa managed to kill them and entered the room where Mori was tied and interrogated. As Fukuzawa recognized the stench of bloodlust lurking within the doctor, Mori killed his interrogators. He then remarked that he pretended to be captured to know the location of their base, which was going according to Natsume's plan. Later, they crushed together a group of mafiosi in a western-style mansion.

During the battle, Fukuzawa defeats Elise, but Mori engages Fukuzawa in a verbal tactic to distract him and stabs him with his scalpel. Meanwhile, Kunikida tells Atsushi about his relationship with Katai and his past when the latter was a member of the Agency. He then tells Atsushi that Katai must be alive, as he left something for Kunikida to indicate that someone had saved him.

Back to the battle, Fukuzawa lays on the ground bleeding to death. A cat suddenly appears at the side, while Mori is about to kill Fukuzawa when the ground suddenly shakes, afterwards collapsing the entire mansion. The cat — Haruno's pet named Mii-chan — turns into none other than Sōseki Natsume, with which Mori and Fukuzawa both gasp in shock. Katai also arrives, and Natsume reveals that Katai has discovered the base of the Rats in the House of the Dead. Natsume then encourages Mori and Fukuzawa to prove to him that they won't let Fyodor destroy either organization they head.