Scorer of 63 tries in 162 appearances for the club, Tuilagi played his last game in Tigers colours in the Aviva Premiership Final at Twickenham last Saturday before preparing to move to the NTT club in Japan next season.
“I have had a very good time at Leicester,” Alesana said.
“This has been home to me for eight years and the supporters have always been great to me.
“The club helped me so much and I am really sad to leave, but I have a big opportunity for my family now.
“I want to say thank-you for all the support during the last eight years and thank-you to all the players.”
Alesana followed older brothers Freddie and Henry into the Leicester squad and became one of the most feared finishers in European rugby, being named supporters’ player of the year in 2007 and ending the 2010/11 as top try-scorer in the Aviva Premiership.
He scored tries for Tigers in four Premiership semi-final victories, as well as in the semi-final and final of the Anglo- Welsh Cup in 2006/07, and regards his two tries and man-of-the-match award in the 2007 Premiership Final victory over Gloucester among his most precious memories of his time in England.
Tuilagi developed a special relationship with supporters at Welford Road, especially on the terrace area in the corner at the Clubhouse End where he celebrated many of his most memorable tries with the fans.
“I have so many special memories of tries in that corner,” Alesana, 31, says. “It is very special to be able to celebrate with the people there who support you so much.”
Tuilagi signed-off at Welford Road with the breakthrough try in the Aviva Premiership semi-final win over Saracens and said: “That was a great feeling, scoring in my last game here.
“Hopefully I will come back soon to watch Manu and to support the boys.”