Sai is Jiyu's father and a ghostwriter of silly samurai dramas. He is often tormented by the memories of his wife, who died at home by Jiyu's side when he used to work in his office. After the incident, he promised to be a better father to Jiyu and subsequently started working at home. Despite his appearance, Sai is in fact talented, he taught Jubei the "Yagyu Shinkageryu Mutodori".

(Wikipedia)