Michizō Tachihara vs. Ōchi Fukuchi

Michizō Tachihara vs. Ōchi Fukuchi is a battle fought between the Hunting Dogs Michizō Tachihara and Ōchi Fukuchi after Tachihara, now having pledged full allegiance to the Port Mafia, has been tasked by Ōgai Mori to defeat Fukuchi, the boss of the Decay of the Angel and true mastermind of the terrorism plot.

It happened at some ruins where Bram Stoker is hidden sometime during the vampire infection outbreak that started in the Mafia courtesy of the Ryunosuke Akutagawa.

Prologue
When Tachihara returned to his Mafia infiltration mission, Mori summoned for him to his office. The boss then places Tachihara's Hunting Dog cap on his head, indicating knowledge of Tachihara's double agent duty. Instead of possibly disposing him as a traitor to the Mafia, Mori turns glad that he has a subordinate who belongs in the police force.

He then reveals how Akiko Yosano divulged Tachihara as a Hunting Dog and how he heard of Atsushi Nakajima's defeat against the true Decay of the Angel mastermind. With Tachihara's theory confirmed, Mori orders him to become a double agent and destroy the world's enemy.

Since then, Tachihara opens a re-investigation recommendation to his fellow Hunting Dogs on the terrorist mastermind. Fukuchi declines his proposal, but Tachihara suggests a contingency plan and reveals the flash drive from the Sky Casino left by Atsushi and his allies, which states the purpose of the Decay of the Angel. Having repaired it with his metal manipulation ability, Tachihara suggests to hand it over to the police who supports the Armed Detective Agency, specifically Deputy Commissioner Yasui.

Fukuchi takes the flash drive to hand it over to Yasui himself and heads to Bram's hiding place in some ruins. The flash drive, in truth, is a tracking device implanted by Tachihara, who now informally defects from being a soldier. He also affirms that Fukuchi shall soon have his downfall, though the latter thinks otherwise.

Battle
Tachihara unsheathes and flings his blade towards Fukuchi, which the latter deflects with Shintō Amenogozen. Fukuchi prepares to attack the past Tachihara with his blade, but Tachihara manipulates the metal sword with his ability and stops it from budging. Fukuchi then utilizes his physical strength to overpower Tachihara, but the latter controls his saber from behind and grazes Fukuchi's neck, causing him to lose grip of Shintō Shintō Amenogozen.

As Tachihara steals Shintō Amenogozen using his ability, Fukuchi praises his ability, though Tachihara does not aim to settle with merely ridding Fukuchi of his sword. He swiftly throws his Hunting Dogs blade once more, which Fukuchi stops with his bare hands and shatters into pieces. As planned by Tachihara, he then manipulates the shards to penetrate through Fukuchi's blood vessels.

With his brute strength, Fukuchi takes out the fragments in his forearm, during which Tachihara flings various shards through his side. Fukuchi then flees to get outside Tachihara's ability range, but Tachihara chases him down while attacking his calf with shards. Fukuchi soon gets backed upon a wall as the shards slowly rise inside his blood vessels.

Tachihara notices an odd "T"-shaped carving on a wall, while Fukuchi praises Tachihara's skills once again. The latter then identifies himself as a mafioso over being a Hunting Dog, though he admits being satisfied as a Hunting Dog if only he did not betray them. As Tachihara presses on in questioning Fukuchi, he suddenly gets pierced from behind.

Apparently, Fukuchi had cut to the past to carve out the "T" shape, which his past self would see as an emergency code. His same past self then cut to the future in front of the "T" code at the exact place where Tachihara would be, which results to the attack on Tachihara from behind.

Fukuchi then blinds Tachihara with his sword to prevent him from further using his ability. Befitting a mafioso, Tachihara urges him to kill him instead rather than have him begging for his life.

Aftermath
In the end, Fukuchi tells Tachihara about the Decay of the Angel' goal, which is to bring painful death to the ""—the politicians—whose indiscretion births war and must therefore be killed and reborn into the cycle. He also notes that they must control half of the world's nations through Bram's ability, which Tachihara is initially in disbelief over until he realizes that Fukuchi can enhance its effect with his ability.

Fukuchi then invites Tachihara to be his subordinate once more as a vampire. Tachihara takes out his blade and attempts to kill himself, only for Fukuchi to grab and stop it. Bram then ends up biting and infecting Tachihara.