The final episode of Bungou Stray Dogs Season 5 begins with a countdown to a catastrophic event threatening 30 million cities worldwide. The atmosphere is tense, and the characters are embroiled in various confrontations and strategic maneuvers.

Fyodor sits in a helicopter, injured but confident in his plans. He acknowledges Dazai as his greatest enemy and mentions Sigma, who was brave but will never wake again. Fyodor intends to take an antidote once he’s in the helicopter and, due to his injuries, asks someone else to pilot it.

On the other side, Dazai works with Rampo and Chuuya to thwart Fyodor’s plans. Dazai reveals that he was shot in the head to deceive Fyodor. It turns out Chuuya was never a vampire. Dazai’s trust in his allies leads to Fyodor’s plans being foiled.

Meanwhile, intense sword fights unfold, featuring various techniques and styles, including Tatsumi-ryu-style katas like Ichinotachi and Ninotachi. Gen'ichiro’s notebook is stolen by Poe, leading to a moment of realization about the gravity of their actions.

Fukuzawa and Gen'ichiro engage in a philosophical discussion about the nature of states and the reasons for war. Gen'ichiro reveals his plan to use the Order of the One to command all the world’s military forces and abolish war. He argues that sacrificing no more than 500 lives to save 210 million lives lost in a future war is a small price to pay.

The episode reaches its climax in a tense standoff between Fukuzawa and Gen'ichiro. Fukuzawa faces a difficult choice: Should he kill Gen'ichiro and become the supreme commander of humanity’s army to save the Detective Agency, or let it perish? Ultimately, Fukuzawa cannot bring himself to kill Gen'ichiro.

The finale ends with an appearance by Akutagawa, hinting that the story begun by Fukuchi Ouchi will only be concluded by the two of them, setting the stage for the next events.