The Highlanders will have to make do without coach Tony Brown for the clash with the British and Irish Lions in June.
Brown will take up a contract with the Japan national team as one of Jamie Joseph’s assistants. The Cherry Blossoms take on Romania on June 10 and Ireland in two matches on June 17 and June 24.
This clashes with the Highlanders-Lions encounter to take place on June 13 at Dunedin’s indoor stadium.
Former All Blacks fly-half Brown has a good understanding of Japanese rugby having plied his trade in the Asian country for three seasons towards the end of his playing career.
The 42-year-old leaves the Highlanders at the end of the Super Rugby campaign and will join the Japan set up full-time.