Kondō Isami
He was a "rōnin" (masterless samurai) from Osaka and an expert in "Katori Ryu". In 1863, he officially joined the Shinsengumi and in 1864, Yamazaki and Shimada Kai were assigned by Kondō Isami to investigate the situation which led to the Ikedaya Jiken on July 8. However, there is a theory that Yamazaki's participation in the Ikedaya Jiken is merely fiction by Shimozawa Kan and Shiba Ryōtarō.