Kasuya was originally a Mito han Ronin, and was one of 24 members of the Rôshigumi who decided to stay in Kyoto, however, he soon deserted and returned to Edo. He joined the Tengutô in 1864 and participated in the Tengutô Rebellion. When the rebellion was defeated Kasuya commited suicide at the Jihô-ji temple.
- Shinsengumi Zentaishi Tettei Guide (新選組全隊士徹底ガイド) Maeda Masaki
- J-Wikipedia Kasuya Shingoro