Jamie Joseph, who represented the All Blacks and Japan as a loose forward in the 1990s, has been coaching the Highlanders since 2011.

The Highlander's Super Rugby winning Head Coach Jamie Joseph will coach Japan.

He will join Japan after the Highlanders complete their Super Rugby season.

Although Joseph's appointment was not supposed to be made at a press conference in Dunedin on Tuesday afternoon, a press release has been placed on the allblacks.com site to confirm the move.

"Obviously we have mixed emotions about Jamie moving on; we would have liked him to sign a new contract with our organisation, however we understand his reasons for signing with Japan," Clark said in the statement.

"After six seasons coaching in Super Rugby the new challenge of international rugby and the opportunity to coach the host nation at a World Cup proved to be too enticing. We couldn't have asked any more of Jamie over the last five years; he has put his heart and soul into this club and delivered a championship."

Joseph, a loose forward who played 20 tests for the All Blacks between 1992-95 and also represented Japan at the 1999 World Cup, will take up the reins in Japan at the completion of the Super Rugby season. He replaces Eddie Jones who guided to Japan to a shock win over South Africa at last year's World Cup. Jones has since been appointed as the head coach of England. He replaced Stuart Lancaster who was sacked after England failed to make the playoffs.

Under Joseph the Highlanders have emerged from being the competition's battlers to a title winner. Last year they beat the Hurricanes 21-14 in the final at Wellington's Westpac Stadium.

"The timing of the announcement is not ideal but it clears up all the speculation of the last few weeks and I know Jamie well enough to know that he will continue to give everything he has to the Highlanders until that final whistle blows. That's just who he is, so we have no concerns as a club on that front" Clark added.

The search for a new head coach will begin in earnest as soon as possible.

Clark commented "clearly in conjunction with the NZRU we will be mapping out a timeline for the appointment of a new head coach. It will be a thorough process and we will ensure the right person is appointed to lead the Highlanders through our next phase."

Joseph, who has strong ties to Japan having also played and coached for Sannix said the decision to leave the Highlanders was not an easy one.

"The decision to move on from the Highlanders was the toughest decision I have ever had to make in my coaching career. The club, the players and the people I have worked with over the last five years mean a great deal to me and the thought of that coming to an end is tough. I take great pride in what this club and all the people within it have been able to achieve in a relatively short time.

"I will always be extremely grateful for the opportunity to have been involved with the club and, no matter which teams I am coaching in the future, the Highlanders will always hold a special place in my heart.

"In a coaching career though you have to keep looking for the next challenge, so you can grow and get better as a coach; for me the challenge of the next few years with Japan is what I need to keep moving forward. International rugby is completely different from coaching at Super Rugby level and brings with it a whole new set of challenges which I am keen to tackle.

While I am looking forward to Japan, for now my focus is still with the Highlanders and ensuring we can build on last year's success"