Sa'u, a former age-group national representative, having played for the New Zealand Under 19s at the 2006 world championships, moved to Japan in 2008 where he has played for Yamaha Jubilo. Last year he played for the Melbourne Rebels during Super Rugby.
He has played 26 times for Japan under Eddie Jones since his selection in 2013, including a key role in the outstanding performances by Japan at the recent Rugby World Cup.
"We are thrilled to have Male join us. He is a strong runner to the line and is now an experienced player at international level," said Blues head coach Tana Umaga.
"Male showed at the World Cup that he is a strong and combative player. He can also play in a number of positions in the backline which is invaluable.
"We have a very young team and Male will add experience as well as undoubted ability."
Sa'u said he was looking forward to the opportunity and being able to spend time in his home city of Auckland with family and friends.
"I have always admired the way the Blues have played and now I also have the chance to play under Tana and the other Blues coaching staff, which I believe will help me with my rugby going forward," said Sa'u.
"I left Counties Manukau before Tana arrived, but I've spoken to some of the guys who have been under him, and they said Tana helped them a lot with their rugby development.
"I am going to give it 100 percent, just hard work. I like the attacking style of the Blues. There will be heaps of new faces there but they can give you that excitement in playing a new style of rugby."
Sa'u is expected to join the Blues next month.