Matsuyama Ikunosuke (松山幾之助)
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. The four of the assassins, including OKAMOTO, voluntarily went to the police later and were pardoned.
This fact was not recorded in the documents compiled by members of Shinsengumi.
Another brief says that the date of his death was April 6, or July 7.