Caol Uno
Joining Naoki Sakurada's Gutsman team, Sakurai made his professional debut in Shooto on October 4, 1996 by submitting Caol Uno. Over the next five years he would go undefeated in eighteen bouts, representing the promotion in three consecutive victories at the renowned Vale Tudo Japan event, as well as French MMA promotion Golden Trophy 1999. Hayato would also win that organization's Shooto Middleweight Champion from Jutaro Nakao, which he defended before Tetsuji Kato.