Akiko Yosano vs. Motojirō Kajii

Akiko Yosano vs. Motojirō Kajii is a battle fought between Armed Detective Agency member Akiko Yosano and Port Mafia member Motojirō Kajii during the Mafia's bounty hunt for Atsushi Nakajima.

It happened in a train through a bombing incident instigated by Kajii to lure out Atsushi among the train passengers.

Prologue
Yosano is accompanied by Atsushi on a shopping trip throughout Yokohama. Meanwhile, after two failed attempts in capturing the weretiger, the Mafia sends Kajii and their assassin Kyōka Izumi to bomb a train that contains Yosano and Atsushi on their way back to the Agency.

After setting off a bomb that claims at least two lives, Kajii calls Atsushi to surrender in exchange for sparing the lives of the other passengers. Yosano and Atsushi then split up to search for and defuse the remaining bombs; Yosano takes up the front of the train and Atsushi the back. As members of the Agency, they also mutually agree to take on the enemy should they encounter them.

Battle
Yosano wonders who the culprit might be, given their audacity to launch a big-scale public attack in broad daylight. As she enters one car in the train, Yosano slips on a lemon-shaped bomb and accidentally triggers its explosion, accompanied by several more blasts. Kajii jestingly greets the Agency member welcome and bids farewell soon after, but Yosano withstands the explosions and accurately recognizes Kajii, known as the Mafia's infamous bomber.

As she identifies him responsible for the Maruzen Building Bombing that claimed 28 lives, Kajii exclaims at such experiment, particularly marveling at the notion and science behind death, which provokes Yosano. As the latter accepts the challenge of taking on her opponent, Kajii releases several lemon bombs, greatly injuring Yosano.

Kajii mocks the Agency for not living up to the rumors of their formidability. He tells her how he perceives death from a scholar's perspective, curious as to why death is irreversible despite the various reversible internal processes it undergoes. Yosano ridicules him for being an idiot, compelling an offended Kajii to stab his knife to Yosano's palm.

He thanks her for her opinion and drops a horde of lemon bombs on her. Knowing that the brain of a person who dies from blood loss remains conscious for eight minutes after death, Kajii momentarily leaves the car, promising to return to her corpse to ask about the feeling of post-death. As he retreats to the driver's cabin, he urges Yosano to take her time dying. Pinned down by the knife on her hand, Yosano gets caught up in the blast.

Following the explosion, Kajii checks on her corpse, only to get punched by a healed Yosano, who finds her punch underwhelming. Amidst his confusion, she lands another punch to even out her attack on his face. Yosano reveals herself as a doctor and answers his question that death is the loss of life, threatening to kill anyone with no respect for human life.

Kajii finally recognizes Yosano as the Agency doctor, and she tells him her ability that can heal all kinds of external wounds, provided that the injured is on the brink of death. As she takes out a large cleaver from her bag, Yosano prepares to "treat" Kajii, much to the latter's horror.

Aftermath
Yosano repeatedly dissects Kajii as part of her interrogation. Eventually, Kajii yields and divulges that the bomb on Atsushi's end can be defused through a remote detonator that Kyōka possesses. Yosano passes the information to Atsushi from the driver's cabin through the PA system, while Kajii lays defeated.

Manga and Anime Differences
The anime contains subtle differences during the event. For instance, the anime depicts a lemon bomb tossed at Yosano as she enters Kajii's train car which sets off an explosion, rather than her shoe heel accidentally pulling the pin off a lemon bomb as illustrated in the manga. Moreover, the manga shows Yosano punctured with glass shards as a result of Kajii's second explosion, which are lessened and reduced in the anime.

Trivia

 * On their way to the train, after Atsushi bumps into Kyōka, he runs into a civilian and drops what appear to be lemons that he and Yosano bought, which seemingly foreshadows the forthcoming lemon bomb explosions in the train.
 * A man slips on the lemons and gets infuriated at Atsushi and later Yosano, who soon manages to scare the man off. The man later appears in the train alongside Atsushi and Yosano, who demand the Agency members to sort out the situation after the first train explosion. He also makes an inappropriate remark at Yosano, causing her to knock him down. This is omitted in the anime.