Yamanami Keisuke (山南 敬助, 1833 - March 20, 1865) was a samurai, secretary general (vice commander) of the Shinsen Gumi, a special police force in Kyoto during the late Edo period.
Although the details of his origin are unclear, he is believed to be the son of a kenjutsu instructor from the Sendai area.
Yamanami was trained by Shūsaku Narimasa Chiba, founder of the Hokushin Itto-ryū school, and attained the Menkyo kaiden ("license of total transmission") sometime before 1860.
In 1860, after his defeat by Kondō Isami in a match, Yamanami Keisuke was enrolled in the dōjō shieikan of the Tennen Rishin-ryū in Edo (headed by Kondō since 1861.) Yamanami was particularly trained in the literary and military arts, with a gentle personality and a good heart.
He is much admired by the chief instructor (jukutou) of the shieikan, as well as by Okita Sōjirō (the future Okita Sōji), who calls him "big brother." In 1863, Yamanami, Kondō and other members of the shieikan joined the rōshi gumi, the military unit sent to Kyoto by the Tokugawa shogunate.
Upon arriving in Kyoto, Kondō and his unit remained in the city while the rest of the rōshi gumi returned to Edo. Soon, the mibu rōshi gumi (which later became the shinsen gumi) was formed. Yamanami serves as vice-commander, alongside Hijikata Toshizō after Niimi Nishiki is demoted for inciting a street fight with sumo wrestlers in Kyoto.
Yamanami is believed to be one of the shieikan members involved in the assassination of Serizawa Kamo in 1863. After the purge of the Serizawa faction, Yamanami became one of the two vice-commanders (the other being Hijikata Toshizo).
Yamanami did not take part in the famous Ikedaya affair in 1864, keeping the group's headquarters.
Some time after the Ikedaya Jiken, he tried to escape from the shinsen gumi in spite of the regulation against deserters. As a result, he committed seppuku for kaishakunin on March 20 (lunar calendar February 23), 1865.
There are several speculations about the reason for Yamanami's desertion, including a theory that Yamanami committed suicide without ever having left the shinsen gumi.
Another theory is that having lost hope for the future of the shogunate and disappointed by the political decisions of Tokugawa Yoshinobu, forced to choose between his friends and justice, Yamanami Keisuke decided to commit an honorable suicide and escape the scandal.
In the book Shinsen gumi: the Shogun's Last Samurai Corps by Romulus Hillsborough, Yamanami's escape is mentioned. The following paragraph is from the book:
"The problem with Yamanami seems to stem from a disagreement of philosophy, although Shimosawa also cites a rivalry with the other vice-commander, Hijikata Toshizo. Yamanami is said to have been offended by the recent smugness of Kondō and Hijikata.
He felt that they had forgotten the original purpose for which the shieikan members enlisted in the "loyal and patriotic" movement. The too-full desire for power that has recently taken hold of his former friends has diminished their former patriotic ideals.
According to most sources, Yamanami's resentment was exacerbated around the beginning of 1865, when Kondō and Hijikata, dissatisfied with their cramped headquarters in Mibu, decided to move to a more spacious location at Nishi Hongan-ji in the southwestern part of the city.
The temple priests were perplexed by this decision. Their attempts to repel the shinsen gumi are ignored by Kondō and Hijikata. Yamanami objects to what he sees as a coercion of Buddhist priests. "Surely there are many other suitable places," he argues to Kondō and suggests that his commander reconsider his decision .
But his commander does not change his mind and Yamanami decides to pay the ultimate price. He composes a farewell letter explaining why he can no longer, in good conscience, risk his life under Kondō's command. Then he defects."
In short, this is the most accepted theory as to why Yamanami leaves the shinsen gumi, although officially it is still a mystery. Moreover, Hillsborough's source for the rivalry between Yamanami and Hijikata, Shimosawa Kan's Shinsengumi Shimatsuki, is actually classified as historical fiction.
Yamanami flees to Ōtsu while Kondō sends Okita to retrieve him. After Yamanami returns to Mibu, he is sentenced to commit seppuku. He asks Okita to serve as his kaishakunin.
One theory is that Kondō Isami asks Okita to serve as Yamanami's kaishakunin out of respect for him. (The kaishakunin is usually a close friend or family member whenever possible.) Yamanami considers Okita as his family and the two share a very strong bond until the end of Yamanami's life.
Yamanami is buried at Kōen-ji (光縁寺) in Kyoto.
Before his death, Yamanami was the second in command of the shinsen gumi. (It is a misconception that Hijikata Toshizo was always the second in command. In fact, Hijikata became second in command after Yamanami's death).