The Japanese side announced on its website yesterday it had secured Dixon's signature.
The Highlanders loose forward will be joined in Japan by Crusaders midfield back Tim Bateman and Waikato forward Jacob Skeen, while Australian back Bryce Hegarty will also play for the Rams.
Dixon's move rules him out of adding to his three All Black test caps. The loose forward showed strong form for the Highlanders in the 2015 title winning season and
after starting the following season well the 29-year-old was selected for the All Black squad for the test series against Wales.
He made his test debut for the All Blacks at Forsyth Barr Stadium in the third test against the Welsh.
The aggressive loose forward then made an appearance off the bench against Argentina in Buenos Aires and scored a try in a test against Italy in Rome.
Last year, he fell down the pecking order as injuries took a toll and he was forced to play behind Liam Squire and Gareth Evans at the Highlanders.
An Achilles injury also hampered his appearances and he only started in half of the Highlanders' games.
He played for Southland in the Mitre 10 Cup and was Southland's best player, but a nasty bicep injury shortened his season and forced him to miss a lot of the Highlanders' pre-season games.
Dixon has only started four games for the Highlanders this season as he has been seen as a bit of a jack of all trades and an impact player off the bench.
He can play all three loose forward positions but his preferred position is blindside flanker. He has played 78 games for the Highlanders and 57 times for Southland.
The Highlanders were keen to keep Dixon, but with the money on offer in Japan and the carrot of All Blacks selection disappearing, Dixon has decided to head north.
The Highlanders have brought in Tasman loose forward Shannon Frizell this season and he has looked impressive.
With the departure of Dixon at the end of the season, and also first five-eighth Lima Sopoaga, there will be only two players - Aaron Smith and Ben Smith- remaining from the 2011 season when the Highlanders started turning things round.
Also yesterday, former Highlanders captain Shane Christie announced his retirement. The 32-year-old was badly concussed in a Highlanders game against the Kings in 2016.
Christie, an openside flanker, played one more 40 minute half for the Highlanders in 2016 but never took to the paddock again.
Stuff reported Christie will be the new Tasman forwards coach in the Mitre 10 Cup this season.
