Ryūnosuke Akutagawa and Atsushi Nakajima vs. Alexander Pushkin

Ryunosuke Akutagawa and Atsushi Nakajima vs. Alexander Pushkin is a skirmish fought between Port Mafia member Ryunosuke Akutagawa and Armed Detective Agency member Atsushi Nakajima against Rats in the House of the Dead member Alexander Pushkin at the height of the Cannibalism operation.

It happened at the Rats' covert base, which is an old coal mine manned by miked and armed guards.

Prologue
After Sōseki Natsume intervenes Yukichi Fukuzawa and Ōgai Mori during their death match, he reveals that Katai Tayama has located the Rats' hideout. Osamu Dazai then has Atsushi and Akutagawa work together in sniffing out Pushkin, while the rest of the Agency and the Mafia look for Fyodor Dostoevsky.

Upon arriving at the coal mine, Akutagawa and Atsushi efficiently infiltrate the base using their respective abilities. Though initially adamant with working together, with Akutagawa even thinking of killing Atsushi under the pretense of getting killed in action, the two soon unwillingly put up with each other in catching the virus ability user.

They soon arrive at crossroads of a surveillance camera and two passing guards. Akutagawa then restrains the latter two with his ability, ordering them to cooperate with them and divulge all intel they know on their employer. One of them, Number Forty-Eight, confesses that he has no idea who their employer is nor what kind of place the mine is, save for a bomb-proof metal door that Atsushi surmises might be the enemy's headquarters.

Battle
As Akutagawa and Atsushi have Katai locate the enemy rather than hacking into the metal door, he soon successfully locates Pushkin two meters behind them. With his companion killed, Number Forty-Eight shoots them and turns out to be Pushkin himself. Atsushi manages to push Akutagawa out of the way, merely grazing Akutagawa's cheek. Pushkin cheerily escapes through a mine cart, while Akutagawa gets infected with the virus.

While a weakened Akutagawa and Atsushi chase Pushkin in a mine cart, Dazai contacts them that the virus can be contracted through small wounds. Pushkin shoots at them, while Atsushi takes cover in the cart. Dazai instructs them not to get Pushkin get away, compelling Akutagawa to try and catch Pushkin with Rashōmon, but to no avail.

Pushkin provokes them and triggers a land mine on their mine cart, much to Akutagawa's frustration. Atsushi then grabs Akutagawa, places him on his back, and chases Pushkin with his tiger-enhanced speed. Pushkin triggers another explosion in the mine, though Atsushi quickly dodges. Just as they are nearing Pushkin's mine cart, a stone giant emerges from the wall and blocks their way, letting Pushkin escape.

Aftermath
Pushkin leaves matters to the stone giant's ability user, Ivan Goncharov, and escapes the mine. Akutagawa motions that they defeat the ability user in a minute, then catch Pushkin once and for all; Akutagawa and Atsushi soon engage Ivan in combat.

Manga and Anime Differences
After Pushkin triggers a land mine on their mine cart, Akutagawa irritatingly admits defeat after Pushkin gets away, after which Atsushi grabs his back to have him ride his back in chasing Pushkin with his tiger speed. On the other hand, the anime portrays Atsushi flinging Akutagawa mid-air during the blast and activating his ability almost simultaneously, with Akutagawa landing on his back.

In the manga, during the chase, Akutagawa constantly grips on Atsushi's ear to "maneuver" his movements, to which Atsushi retorts that he is not a steering wheel. Atsushi's complaint is not shown in the anime, and Akutagawa grips on his collar all throughout the chase. The anime also adds Akutagawa using Rashōmon along the chase in cutting down debris from the ceiling from explosions triggered by Pushkin, which does not occur in the manga.

As a minor difference, Pushkin in the anime tells Atsushi and Akutagawa that they are too late despite getting near him, while he does not say any foreboding hints in the manga before Ivan strikes. The manga also portrays the stone giant emerging from the wall, blocking their way, and punching Akutagawa and Atsushi away from Pushkin. Meanwhile, in the anime, the stone giant punches the two to a nearby open ground in the mine and appears to have emerged from the ground.