- Birth: 1843
- Death: 1875?
- Ranks: Hakodate Shinsengumi Commander
- Other names: Sôma Hajime (相馬 肇), Sôma Tonomo (相馬 主殿)
- Japanese: 相馬 主計 (Souma Kazue)
Sôma Kazue was the son of Funabashi Heihachirô of Kasama han in Hitachi province. He joined the Shinsengumi in the 10th month of 1867. When Kondô Isami was captured, Kazue brought a letter from Matsunami Gonnojô to Kondô in Itabashi, however he was not allowed to see Kondô and was imprisoned. He met Nomura Risaburô in the same prison. They were released after Kondô was executed and they headed to Ezo with the Bakufu's Rikuguntai. (They joined back up with the Shinsengumi in Sendai)
In 1869/5/11 Hijikata Toshizô was killed and Sôma became the last commander of the Shinsengumi. He was exiled to Nijima island after the Boshin War. He married on the island and they moved to Tokyo in 1873.
in 1875 his wife Matsu found him dead in their house, having comitted seppuku.
- Shinsengumi - Honor and Determination of the Mibu Rôshi (血誠新撰組-峻烈壬生浪士忠と斬), Rekishi Gunzô series #31, Gakken, Japan, 2003
- Shinsengumi Zentaishi Tettei Guide (新選組全隊士徹底ガイド) Maeda Masaki
- Shinsengumi Taishi Den (新選組隊士伝) Gakken