Armed Detective Agency vs. Hunting Dogs

The battle of the Armed Detective Agency vs. Hunting Dogs is the first confrontation of the framed Armed Detective Agency members as the terrorist Decay of Angels against the Hunting Dogs dispatched by the government.

While on the run, the Agency members including Doppo Kunikida, Akiko Yosano, Kenji Miyazawa, and Jun'ichirō Tanizaki face the Hunting Dogs Saigiku Jōno and Tetchō Suehiro. It happened on the road of a southern highway as anticipated by the Hunting Dogs.

Prologue
After being framed as terrorists, the major Agency members set out to run from the police forces. Though initially stumped, they soon agree on a decision to first survive against their pursuers, boiling down whether to board at a northern train station or to seize a vehicle down a southern highway to get away. Kunikida, as their de facto leader, chooses they go down the highway to minimize possible casualties if they are to encounter the military police.

At the same time, the Hunting Dogs anticipate their options and separate into two teams: Ōchi Fukuchi and Teruko Okura head north, while Jōno and Tetchō go south.

Battle
The Agency soon hijacks a getaway car and think of possible hideouts they can go to. Before they can come up with a solid decision, Jōno tracks them down and uses his ability to infiltrate the Agency car by atomizing himself into particles. Kenji instantly punches Jōno with his super strength, but Jōno almost effortlessly blocks it and kicks Kenji out of the car.

An enraged Tanizaki activates Light Snow and invisibly drags Jōno out of the vehicle, though the latter asserts that he had him take him out on purpose. Jōno then instructs Tetchō, the Hunting Dogs' greatest swordsman, to dispatch the two Agency members. However, Kunikida quickly rams the vehicle to Tetchō, swearing by his ideals that no subordinate gets left behind.

Kunikida then lets Kenji grab on the vehicle with Tanizaki at full speed, afterwards panicking at the thought of facing the Hunting Dogs, the military police's ultimate trump card. Meanwhile, Tetchō affirms that he has now warmed up; brandishing his sword towards the Agency car, he activates his ability and completely halves the car.

With the Agency members heavily injured, Tetchō swiftly approaches and attacks Kenji and Tanizaki. Kunikida attempts to materialize a stun grenade, but he—along with his notebook—also gets slashed. He then realizes at the last minute that Tetchō's ability allows him to extend his blade, musing how the Hunting Dogs are too powerful.

With the three subdued, Jōno asks Tetchō to kill Yosano to prevent her from healing her subordinates and to rid the world of the "Angel of Death", a moniker that Yosano is shocked to hear Jōno mention. Kunikida surrenders in exchange for sparing Yosano's life, only for Jōno to remark how he senses relief from the idealist's heartbeat and that his ideals are broad and lofty as a balloon, which is soon bound to fall off the ground once it runs out of fuel.

Suddenly, upon orders of Ōgai Mori as part of a negotiation with Yukichi Fukuzawa, Chūya Nakahara shoots Tetchō with gravity-manipulated bullets, an attack that even Jōno failed to sense. Aboard a chopper, Chūya lands a barrage of attacks on the Hunting Dogs, while the Agency members board the chopper.

Chūya clarifies that his intervention is part of a negotiation that Mori had struck with Fukuzawa, which involves the transfer of an Agency member to the Port Mafia. Initially in disbelief, the Agency members especially Kunikida admit that they must indeed face their reality. As he further ponders on what Jōno mentioned earlier about his ideals, they soon find Kenji impaled with Tetchō's sword at such high altitude, the latter still bent on pursuing them. Tetchō bends his sword on Kenji and hangs on the chopper, eventually reaching its and attempting to cut down the.

Without any further reluctance, Kunikida entrusts Tanizaki with finding the real criminal before jumping off the chopper to land on Tetchō. The Hunting Dog chides his foolishness, but Kunikida assures him that he is the fool for thinking his schedule can be ruined. Using an emergency page, Kunikida reaffirms his ideals and manifests a hand grenade. Clutching it on Tetchō as his shield, Kunikida then sets it off into an explosion, much to Tanizaki's horror.

Aftermath
The Agency members manage to get away and reach a Mafia, later welcomed by Mori himself. They also learn from him that Osamu Dazai has been arrested by the Hunting Dogs and transferred from various institutions and departments, though his latest fate remains unknown to them.

Meanwhile, Kunikida suffers an amputation on both arms following his sacrifice. Later taken to the hospital and presumably arrested, Jōno visits him during the coin bomb explosions overseas. He praises Kunikida's talent for surviving the blast, hence deciding to have him acquitted alone. In exchange, Jōno invites him to join the Hunting Dogs and track down their remaining Agency targets; naturally, Kunikida bluntly refuses his offer.

Upon leaving, Jōno tosses him his broken notebook and informs him that Yosano (who later gets cornered and arrested herself) is due for execution. He then wonders how Kunikida can continue to uphold his ideals given their situation, leaving the helpless Kunikida behind.