In episode 4 of Bungo Stray Dogs Season 5, titled "Hero War, Gang War," the plot escalates further, and the battle against the terrifying antagonist Fukuchi takes unexpected turns.

The episode begins after a fierce fight in which Akutagawa loses his life to Fukuchi. Atsushi, expressing his pain and despair, manages to retreat with an evacuation submarine, narrowly escaping Fukuchi's grasp. Fukuchi considers pursuing Atsushi, but the arrival of the ship's guards diverts his attention.

The narrative then reveals crucial information—the identity of the fifth member of the Decay of Angels. The member turns out to be Bram Stoker, also known as the "Undead King." He has a vampire-like appearance and can turn others into vampires by biting them.

After this revelation, Fukuchi takes an unexpected step. He instructs Bram Stoker to bite Akutagawa's corpse, thereby turning him into a vampire. This action not only revives Akutagawa but also triggers a horrific vampire plague.

Elsewhere, a major plot twist occurs. Tachihara, a member of the Port Mafia, exposes Fukuchi as the mastermind behind the Decay of Angels. After his cover is blown, his boss Mori delivers this crucial information to him. Instead of punishing Tachihara, Mori recruits him as a double agent.

In a final confrontation between Tachihara and Fukuchi, the latter once again demonstrates his cunning strategy. He uses his space-time sword to execute a planned attack that catches Tachihara off guard, severely wounding him. Fukuchi blinds Tachihara and allows Bram to turn him into a vampire, hinting at an impending global vampire invasion.