Ichiyō Higuchi and Black Lizard vs. Foreign Mercenary Group

Ichiyō Higuchi and Black Lizard vs. Foreign Mercenary Group is a battle fought between Port Mafia operative Ichiyō Higuchi and the Black Lizard against a group of foreign mercenaries hired by the remnants of Karma Transit after abducting a comatose Ryunosuke Akutagawa out of grudge.

It happened somewhere in Yokohama's warehouse street after the failure of the Mafia's bounty operation in capturing Atsushi Nakajima.

Prologue
During the Mafia's capture of Atsushi, the Mafia employs Karma Transit to transport Atsushi in one of their trucks to the Mafia's cargo ship. At some point, Akutagawa slaughters the members of Karma Transit in their headquarters as discovered by Armed Detective Agency member Jun'ichirō Tanizaki.

Eventually, remnants of Karma Transit hire a group of foreign mercenaries, with strength in numbers and firearm resources, to take on Akutagawa apparently out of revenge. Incidentally, with Akutagawa comatose after his battle with Atsushi, the mercenaries abduct him at night and bring him to their base. Higuchi is soon notified of the abduction and head straight to the armory in an attempt to retrieve her superior.

Black Lizard commanders Ryūrō Hirotsu, Michizō Tachihara, and Gin dissuade her from going, urging her to await orders from the higher-ups on a retrieval operation. However, knowing that a possible large-scale conflict might break out with an entire foreign organization striking back at the Mafia out of a personal grudge against Akutagawa, Higuchi deduces that the orders shall not come and instead let the conflict unfold under the pretense of a case of personal vengeance on an individual mafioso. As a result, Higuchi rushes to the warehouse district to face the foreign mercenaries on her own.

Battle
Upon arriving at a warehouse, an anxious Higuchi tosses a grenade through the open doorway. Afterwards, she storms the warehouse and opens fire at the mercenaries using her submachine gun, hitting various targets. Higuchi eventually gets shot on her right thigh, forcing her to take cover behind a wooden crate.

Despite her wound, Higuchi steels her resolve to save Akutagawa and fires at her opponents, though she gets disarmed by an opponent's shot. Soon after, to her surprise, the Black Lizard arrives to aid her, with Tachihara ordering his subordinates to kill all enemies. Gin slashes through the mercenaries, Tachihara shoots with precise accuracy towards his opponents, and Hirotsu blasts them away. Higuchi asks why they have arrived, to which Hirotsu tells her that they cannot simply do nothing with their superior in danger.

Aftermath
With the Black Lizard having exterminated all mercenaries, Higuchi hears Akutagawa conscious on his stretcher bed and makes way towards him. She tries to wipe the blood on Akutagawa's face, but he catches her hand and thanks her. A teary-eyed Higuchi smiles and mentions that she is merely doing her job, while the Black Lizard commanders stand by outside the room.

Manga and Anime Differences
There are various subtle differences in the anime from the manga. In the manga, Higuchi acquires her thigh wound in the midst of the shootout and immediately takes cover; in the anime, a mercenary climbs on top of a crate near her and shoots her on the thigh before getting shot as well.

Later, unlike in the manga, Higuchi further gets shot on her right shoulder after getting her submachine gun knocked off and surrounded by the mercenaries in the anime, right before the Black Lizard arrives.

When the Mafia kills all the enemies, Higuchi limps straight to Akutagawa who remains unconscious; while he is already conscious by the time Higuchi heads to the room in the manga, he awakens only when Higuchi calls him in the anime. Furthermore, when Higuchi tries to wipe off the blood off his face, Akutagawa grabs her hand and thanks her in the manga. Meanwhile, he apologizes to her in the anime, to which she replies that she is only doing her job.