A lot of us think of Hijikata as the last Commander in the Shinsengumi, it’s probably more appropriate to say that Hijikata-san was the last Shinsengumi Commander to die in the battlefield as four days after his death, Souma Kazue was appointed as the Commander of the Shinsengumi troop that had surrendered in Benten Daiba and Goryokaku along with the Hakodate army. He was appointed as the commander of the Shinsengumi by the Hakodate magistrate “Nagai” most probably because of the concern that confusion would happen after the surrender and they needed a familiar person in charge. Souma is described to have a been quite an Aide to the former commander Hijikata.
For the most part Souma Kazue was a common member of the Shinsengumi, he was the son of Heihachirou who was a Hitachi Kasama feudal soldier who joined around 1863. There is no record of “remarkable” work in either Toba-Fushimi, Edo nor Kyoto. When Kondo was captured, Hijikata instructed Souma to deliver a letter to Kondou in Itabashi and he went there under the name “Hajime Souma” but was caught. Since he was considered as an unimportant person by the enemy, they released him when Kondou was executed. After this Souma joined several troops including those in Sendai but after Sendai’s defeat he fled on one of Enomoto’s ship and sailed to Ezo to continue the fight there. It’s there that Hijikata who was now an army magistrate, saw him and took him into his team and Souma proved to be a matchless aide to Hijikata and thus Souma became a natural pick to succeed Hijikata to organize the surrender of the Shinsengumi under the Hakodate army.
However this appointment would affect him adversely and he is sent to Tokyo along with Enomoto, Arai and Matsudaira Taro to be investigated as the masterminds of the Hakodate war that June. He is banished to Niijima, Izu Nanashima in 1870 where he changed his name to either Tsukasa or Tonomo (apologies, I can’t make out the proper name, it’s one of those two. *sad*). There he married Uemura lived there for two years until he was pardoned in 1872 and re-appears in Tokyo. According to Akama’s interview with Matsuno, a descendant of Uemura he died in the following manner… Souma Kazue asked the others to do minor errands and when they left he commited seppuku. When the others returned the room was filled with a sea of blood and the shoji had been dyed red like the evening glow. However it is unknown why he had committed suicide nor the place he was buried and what date.
The details about Souma Kazue came from Suzuki Tooru who cited works of Kiichi Sato’s “Shinsengumi Taishi Retsuden” and Akama’s “Rekishi Tabi”.