On July 6, 1864, Matsuyama, who had been stationed to Okuichiya, Okayama (Prefecture), as Shinsengumi's spy to investigate into the movement in the western regions, was murdered by seven roshi (masterless samurai) represented by Taro OKAMOTO, and his head was shown in public at the Onari Bridge in Ipponmatsu.
1864年7月6日、松山は、新選組の密偵として西国の動きを探るため、岡山奥市谷に潜入していたが、岡元太郎ら7名の浪士に斬殺され、一本松の御成橋に梟首される。