|Voice actor||Tomichi Nishimura (Japanese)|
Brice Armstrong (English)
Masamune is Kikuchiyo's mechanic and a veteran of the Great War. As the series progresses, he befriends Kambei and the other samurai while they stayed in Kogakyo. He was the one who helped them escape from the city, although he was tied up by Kambei and "roughened up" by Kikuchiyo as a ploy to trick the attendants into believing that Masamune was taken hostage rather than willingly aiding the samurai. The samurai later on still run into him again.