Plumtree would join fellow New Zealander Jamie Joseph's staff as a defence coach for a non-test match against a World XV on Oct. 28 and then for three tests in November, the Hurricanes said.
"I see my coaching future as being firmly with the Hurricanes, but I jumped at the chance when Japan approached me about the prospect of coaching at international level," Plumtree said in a Hurricanes' statement on Monday.
"It's a great opportunity to be exposed to a new culture and new ways of coaching."
Joseph, who was named as the coach of the country's Super Rugby Sunwolves team as well last week, has already recruited his former Otago Highlanders assistant Tony Brown to his staff. Both are contracted until the 2019 Rugby World Cup in Japan.
"Japan has a strong coaching team with Jamie Joseph and Tony Brown, and working alongside them will only add to the knowledge and experience I can add to the Hurricanes going forward," Plumtree added.
Plumtree was the forwards coach for Ireland before he returned to New Zealand to join the Hurricanes in 2015.
Japan host Australia in Yokohama on Nov. 4, then play Tonga on Nov. 18 and France in Lille a week later.
(Reporting by Greg Stutchbury; Editing by John O'Brien; Editing by xxxxxxx)
