Sasuke is the story of a ninja child that starts right after the battle of Sekigahara where Tokugawa Ieyasu becomes shogun of Japan. Sarutobi Sasuke (Jump Like Monkey Sasuke) was a famous ninja in the employ of Sanada Daisuke who fought for the losing side against Ieyasu. He was believed to have committed suicide when he was trapped in a castle, but the story takes off that he really escaped and that Sarutobi is not a name of a ninja but a whole ninja clan.

(Source: AniDB)