Sasaki Ryujiro (佐々木 龍) is the sadistic, mentally unbalanced subordinate to Shibui Matsunosuke, the corrupt magistrate of an oppressed town, who assigns him to protect his bratty son, Tomonoshin.
Sasaki has brown hair tied back in a pony tail that goes down to the bottom of his neck. He has a beard that is about the same width as his mouth and rises in the middle. He wears a dark blue kimono.
He started wearing some wraps on his right arm stump after Mugen cut his hand off.
Ryujiro is cold and has a ruthless sadism that predates the loss of his arm, however after losing it he seems even more cruel and unstable, claiming to Fuu that he lost his humanity a long time ago and has no problem with killing and torturing his opponents. He is vengeful and manipulative, using Oniwakamaru's huge size and appearance against innocents, tailing Mugen, Fuu and Jin to make Mugen pay for what he did to his arm, and he has no qualms with taking Fuu hostage as a leverage.
Ryujiro's right arm is chopped off by Mugen after the altercation in the teahouse, driving him insane. He burns the teahouse down in retaliation, inadvertently killing the magistrate's son, leaving Fuu unemployed and Jin and Mugen are thrown in prison as the culprits. As they are later saved by Fuu and swear to travel along with her, Ryujiro's actions could be considered the starting point of the series.