John Kirwan has confirmed he will quit as Japan coach when his contract expires in December.
The former All Blacks winger failed to lead his side to a win at the Rugby World Cup in his home nation, with losses to New Zealand (83-7), France (47-21), Tonga (31-18) and a draw against Canada (23-23).
"I have thoroughly enjoyed my time with Japan Rugby and will always be very proud of the improvements and achievements we have made," Kirwan said in a statement released by the Japan Rugby Football Union (JRFU).
"I will always follow the JRFU with interest and remain very grateful for the opportunity to serve Japan."
JRFU chairman Tatsuzo Yabe said Kirwan's departure came as a result of their fruitless Cup campaign in New Zealand.
"Although his achievements since he joined the JRFU was great, it is also true that we must face the result of the RWC 2011 frankly and severely," Yabe said.
"There still are tons of improvements we have to make … It is our paramount challenge to review our current high performance structure thoroughly immediately."
Kirwan's departure comes as Japan look to build towards their the 2019 World Cup, of which they are co-hosts, meaning there will be some pressure on an improved showing from Japan when the tournament heads to England.
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