Ôishi was called "Hitokiri Kuwajiro" because of his involvement in many assassinations by the Shinsengumi. In March 1868, he fled the Shinsengumi and tried to join Satsuma han troops. But he was captured and executed on the charge of murder of Ito Kashitaro.
References
- Shinsengumi Zentaishi Tettei Guide (新選組全隊士徹底ガイド) Maeda Masaki