Yukichi Fukuzawa vs. Ōgai Mori (Post-War)

The battle of Yukichi Fukuzawa vs. Ōgai Mori after the Great War is fought between Armed Detective Agency president Yukichi Fukuzawa and then Port Mafia retainer physician Ōgai Mori over the custody of Akiko Yosano.

It happened about three years after the war ended, during which Yosano was isolated in an institution with psychological trauma. This battle would also mark the end of the alliance between Fukuzawa and Mori.

Prologue
During the war, Yosano worked as a military hospital student after being drafted by Mori, then an assistant military physician. Her healing ability paved way to Mori's "Immortal Regiment" scheme that enabled the soldiers to continue fighting amidst casualties and traumatic war experience. As the war ended, Yosano became traumatized and was confined in an isolation institution.

Mori eventually found her and wished to take her under his tutelage once more to use her ability as a way of reviving his "Immortal Regiment". Specifically, he planned to use it to overthrow the then Port Mafia boss who had been causing violence and chaos throughout the city, deeming this as a way of upholding the Tripartite Framework. At some point, Fukuzawa, president of the newly-established Armed Detective Agency, apparently got wind of his plan and interfered.

Battle

 *  Note: The details from the beginning of this battle are not shown. 

Fukuzawa's swordsmanship and Mori's own physical prowess, backed by his offensive ability, soon yielded a momentary stalemate. Fukuzawa criticized Mori for planning to drag Yosano back into a hellish experience again, but Mori retorts that she is the only way that can revive another "Immortal Regiment" to overthrow the Port Mafia boss and thereby bring peace to Yokohama. Fukuzawa condemns Mori's heartless logic, but Mori claims that they are at war; hence, there is no place for having "heart" as long as victory can be secured. The two clash once more, with Fukuzawa dissolving his alliance with Mori.

Meanwhile, the then sole member of the Agency Ranpo Edogawa takes Yosano somewhere safe and escape. Though Yosano is initially adamant in going with him in fear of using her ability and claim lives of more people, Ranpo ultimately manages to persuade her into joining the Agency and to use her kindness rather than her ability.

Aftermath
Though the battle's conclusion is left unknown, it is nonetheless apparent that Mori lost in taking Yosano for his plans. From then on, Yosano joins the Agency alongside Fukuzawa and Ranpo.