The Assassination of Serizawa Kamo

Serizawa Kamo and the Internal Strife of the Early Shinsengumi

In 1863 (Bunkyū 3), the Rōshigumi — a band of masterless samurai recruited in Edo ostensibly to guard Shogun Tokugawa Iemochi's journey to Kyoto — fractured almost immediately after arriving in the city over the true intentions of its organizer, Kiyokawa Hachirō. A faction that refused to return to Edo and insisted on remaining in Kyoto formed the Mibu Rōshigumi. One of its leading figures was Serizawa Kamo, said to hail from Mito domain and known as a swordsman of the Shintō Munen-ryū school, with reported ties to the Mito Tengu-tō. The Mibu Rōshigumi was an unstable coalition of two factions with different origins and temperaments: one centered on Kondō Isami, Hijikata Toshizō, and Okita Sōji, all from the Shieikan dojo of the Tennen Rishin-ryū school, and the other centered on Serizawa Kamo, Niimi Nishiki, and Hirayama Gorō, all with ties to Mito domain. Initially, Serizawa of the Mito faction stood as the senior commander, with Kondō in a subordinate position. In the eighth month of that year, the group was placed under the patronage of the Kyoto Shugoshoku, Aizu domain lord Matsudaira Katamori, and received the name "Shinsengumi" to serve in policing the city — yet the power struggle between Serizawa and Kondō continued to simmer beneath the surface.

At a time when assassinations of officials and attacks on foreigners by radical sonnō jōi activists were rampant and Kyoto's public order had badly deteriorated, Aizu domain relied on the Shinsengumi as an active police force, which meant the group had to prioritize discipline and its public reputation above all else. Serizawa was a capable swordsman, but is said to have repeatedly caused trouble through his conduct: violent outbursts at teahouses and brothels in Gion and Shimabara, a brawl with sumo wrestlers from Osaka, and an arson incident targeting the silk merchant Yamatoya Shōbei sparked by a trumped-up grievance — all incidents that threatened to damage the Shinsengumi's overall reputation in Kyoto. Niimi Nishiki, another senior Mito-faction commander, had already been forced to commit seppuku by the Kondō-Hijikata faction that same eighth month on charges of violating group discipline (unauthorized visits to teahouses), and the Mito faction's power was already being eroded. Kondō and Hijikata, needing to preserve Aizu domain's trust, are said to have come to view Serizawa's very presence as a danger to the organization. Some also hold that the Mito-domain network Serizawa was tied to was itself viewed with suspicion by Aizu domain and the shogunate, and that Kondō and Hijikata's motives extended beyond Serizawa's individual misconduct to a political desire to purge the Mito faction as a whole from the Shinsengumi.

The Night Before — The Banquet at the Sumiya and the Yagi Residence

On the night of the 16th day of the ninth month of Bunkyū 3 (some accounts say the 18th), the Shinsengumi held a banquet at the Sumiya, a licensed teahouse in Shimabara. While the Kondō faction remained at the party, Serizawa is said to have left early with his close associate Hirayama Gorō and returned to the Yagi Gen'nojō residence in Mibu, the group's billet, to continue drinking there. His mistress Oume and geisha summoned from the neighborhood reportedly joined this second gathering. Late that night, the heavily intoxicated Serizawa and Hirayama each retired to rest within the Yagi residence — but the prevailing view holds that the Sumiya banquet itself had been arranged by the Kondō-Hijikata faction to lower Serizawa's guard and create an opportunity for his assassination. As a group under Aizu domain's formal patronage, the Shinsengumi could not be seen to be riven by open internal conflict, so any reckoning had to be carried out in secret, and with certainty.

The Assassination

Amid a storm late that night, several men reportedly broke into Serizawa's sleeping quarters at the Yagi residence. Hirayama Gorō, asleep in the adjoining room, was cut down first, suffering wounds severe enough to nearly sever his head from his body. Alerted by the noise, Serizawa, naked, tried to flee into the next room but tripped over a low writing desk and fell, whereupon the assassins cut him down repeatedly. His mistress Oume, sharing his bedding, was killed as well in the attack, while another close associate, Hirama Jūsuke, who was in a separate room, is said to have escaped unharmed.

Accounts differ as to who carried out the killing. Records based on the testimony of Shinsengumi member Nagakura Shinpachi name Hijikata Toshizō, Okita Sōji, Tōdō Heisuke, and Mikura Isetake, while other traditions implicate Yamanami Keisuke or Harada Sanosuke — the exact roster of assailants remains unconfirmed. The date, too, is given variously as the 16th or the 18th, with limited corroborating evidence for either. Whichever account is followed, most agree that the operation was driven at its core by Hijikata Toshizō, Kondō Isami's most trusted lieutenant.

The Aftermath and the Official Cover Story

The Shinsengumi reportedly reported the incident to Aizu domain as an attack by hostile rōnin or radical sonnō jōi activists then rampant in Kyoto, rather than an internal purge. Serizawa and Hirayama were given proper funerals as fallen members of the corps, and the affair was officially treated as a mysterious death among comrades. This kept the true nature of the internal purge from becoming public knowledge for the time being and preserved Aizu domain's trust in the group. The incident marked the point at which Kondō Isami became, in fact as well as in name, sole commander of the Shinsengumi, with Hijikata Toshizō supporting him as vice-commander — the Kondō-Hijikata command structure that would define the organization thereafter. From this point, the Shinsengumi strictly enforced its internal code (the Kyokuchū Hattō) and reorganized into the tightly disciplined force under Kondō's command that would go on to police the streets of Kyoto, as it is remembered in history.

The Sword Serizawa Is Said to Have Carried

Serizawa is said to have been a skilled swordsman of the Shintō Munen-ryū style, but on the night of his death, heavily drunk, he reportedly had no chance to reach for a weapon before he was cut down. Among swords associated with the Shinsengumi, Kondō Isami's "Kotetsu" blade (attributed to Nagasone Kotetsu, though its authenticity remains disputed) is by far the most famous; reliable primary-source provenance for any sword personally carried by Serizawa is scarce, and much of what circulates today owes more to later novels and period dramas than to verified history. A sword cut preserved in a pillar at the Yagi residence still stands today as one of the few physical traces of the incident's violence.

Historiographical Notes

Two broad interpretations of the incident's background have come down to us. One holds that Aizu domain, exasperated by Serizawa's repeated misconduct, quietly ordered his removal; the other holds that it was a purely internal power struggle engineered by the Kondō-Hijikata faction to seize full control of the Shinsengumi. These explanations are not mutually exclusive, and a hybrid reading — that Kondō and Hijikata acted against a backdrop of Aizu's tacit approval — is widely accepted. In any case, most surviving accounts derive from memoirs and secondhand records compiled after the fact rather than from contemporaneous primary sources, which is why competing theories about the perpetrators and motive continue to coexist.

Historical Significance and Later Influence

The assassination of Serizawa Kamo is regarded as the decisive turning point at which the Shinsengumi transformed from a loose coalition of rōnin brought from Edo into a tightly disciplined armed organization under Kondō and Hijikata. Some researchers argue that this purge set a precedent that shaped the Shinsengumi's subsequent pattern of enforcing its code through internal purges, influencing later episodes such as the flight and forced suicide of Yamanami Keisuke and the 1867 Aburanokōji Incident, in which Itō Kashitarō and his Goryō Eishi followers were killed. The Yagi residence is preserved today in Mibu, Nakagyō Ward, Kyoto, and is open to the public along with its sword-scarred pillar as a Shinsengumi-related historic site. The establishment of the Kondō-Hijikata command structure is also seen as having provided the organizational foundation for the Shinsengumi's subsequent operations, including the Ikedaya Incident, making this assassination a pivotal episode in the history of law and order in bakumatsu-era Kyoto.