Oroku Saki was a Japanese martial arts master who trained under Grandmaster Yutani.  Oroku Saki was also secretly a member of the ancient Foot Clan.  He saw that many of the Grandmaster’s students would join the Foot, but not as long as the Grandmaster was around.  So he murdered Grandmaster Yutani and framed Hamato Yoshi, who he knew would never join the Foot Clan.   So successful was Oroku Saki’s ploy in gathering talented followers for the Foot Clan that he was sent to America to take over the dwindling Foot Clan in New York City.  There, he quickly learned that it was theatrics and charisma that would draw followers, not merely skill and the promise of power.  So he took on the persona of the Shredder, a criminal mastermind.