The content below is entirely editable.
The little sister of Jinno who stole the Number One headband and led a complex plot to gain revenge on the Afro Samurai with her resurrected brother and Afro's resurrected father.
Sio is the little sister of Jinnosuke, who only appears in Afro Samurai: Resurrection. While Jinno was studying at a dojo with Afro Samurai, Sio apparently went to live with another family elsewhere. She briefly visited the dojo to say hello to Jinno and seemed to like the young Afro.
Sometime after the events of the original series, Sio launched a complicated scheme on her brother's behalf to take revenge on the Afro Samurai. With the help of Professor Dharman, she and her resurrected brother robbed the grave of Afro's father, took the Number One headband, and then went to resurrect his father for the sole purpose of humiliating him. As Afro went to seek revenge, Sio continuously taunted him just to enlarge his suffering. She almost got her revenge when Afro's revived father managed to kill him, until Jinno died trying to protect Afro, and then Sio died trying to protect him.
Sio apparently learned to wield a tanto in combat, but she seems to be more of the manipulative type, letting others do the work for her. It explains why Sio died so quickly during her one real fight scene.