(Adds details, quotes)
By Shinichi Saoshiro
TOKYO, June 24 (Reuters) - Ireland ran five tries past Japan for a 35-13 win to sweep the two-test series on Saturday, a performance they will hope to repeat when the two sides meet again at the 2019 World Cup.
The tourists struck in the third minute through a try by centre Gary Ringrose who finished off an interception which the visitors won in Japan's half.
Ireland scored three more tries in the first half through Josh van der Flier, Kieran Marmion and captain Rhys Ruddock.
Japan hit back in the 23rd minute after the hosts won a line out deep in Irish territory, setting up a rampaging run by lock Uwe Helu which centre Kotaro Matsushima completed with a sweeping try in the right corner.
Jumpei Ogura also converted a penalty in the half past to add three points for Japan.
The home side came back with more intent in the second half, which it dominated for long stretches by kicking less and keeping the ball in hand.
Wing Akihito Yamada pounced on a chip kick from Rikiya Matsuda to touch down on the right corner in the 62nd minute.
While Japan's performance was an improvement since being thrashed by Ireland 50-22 a week ago in Shizuoka, their comeback stalled after Yamada's try.
Although the visiting side, shorn of 11 players away on British and Irish Lions duty in New Zealand, began to tire under the hot and humid conditions, they never let off the gas.
"We really felt the mental strength of a top three side. While other sides may have given up, Ireland never cracked under today's heat," said Japan skipper Michael Leitch.
Ireland coach Joe Schmidt conceded heat was a factor with a developmental side that featured eight players winning their first cap on this tour, along with the valuable experience of the local conditions ahead of the 2019 World Cup.
"It was very hot out there, players were fatiguing early in the game. So it was good to get a good start and hang on to the game," Schmidt told reporters.
A try by replacement Irish flanker Sean Reidy two minutes from the hooter killed off the Japanese fightback, much to the disappointment of the 29,354 fans gathered at the Ajinomoto Stadium.
Paddy Jackson was unerring with the boot, converting all five of the tries scored by Ireland.
For Japan coach Jamie Joseph, the two successive losses against a tier-one side highlighted the challenges his team needs to overcome if the 2019 World Cup hosts are to advance to the knock out phases.
Along with Ireland, Japan is also placed with Scotland in its preliminary group.
Joseph said Japan's defence performed admirably but added that "accuracy really cost us and we gave away too many penalties."
"I thought we defended very well but the Irish guys were just much bigger than us. They played very simple rugby and effectively just overpowered us," he told reporters.
"In the past we challenged that by adding foreign players and that will always be an area of challenge for Japanese rugby." (Reporting by Shinichi Saoshiro; editing by Amlan Chakraborty)