Ireland beat Japan 35-13 on Saturday to sweep their two-game series despite a rousing second-half performance by the 2019 Rugby World Cup hosts.
Ireland thrashed Japan 50-22 in the opening game in Shizuoka the previous weekend and the visitors wasted little time in establishing their superiority at Tokyo's Ajinomoto Stadium, scoring four first-half tries to Japan's one from Kotaro Matsushima.
But a hugely improved effort after the break saw Japan hold world No. 3 Ireland scoreless for all but the final two minutes of the second half, even if a 62nd-minute Akihito Yamada try was not enough to spark the Brave Blossoms to a famous victory.
"Obviously the players are disappointed to lose the test match but I think we showed our ability against a very strong team," said Japan head coach Jamie Joseph. "I felt that the Ireland team was very strong and they took their opportunities. That put us under pressure but I'm very proud of the boys for the way they ended the game.
"We had some young players in this series and they have really stepped up and shown that they can play at this level. That's a good sign for the World Cup."
Japan and Ireland will face each other again in Pool A at the 2019 World Cup, and Ireland head coach Joe Schmidt stressed that he has no intention of taking the Brave Blossoms lightly despite his team winning both games this month without 11 players on British and Irish Lions duty.
"I think, having just spoken to the players, that was very, very tough going," said Schmidt. "The Japanese defense were very quick off the line and very effective in the tackle. They made it very hard work.
"It was very hot and players were fatiguing early in the game. So it was good to get a good start and hang on at the finish."
Japan got off to the worst possible start when Amanaki Lelei Mafi's errant pass to Jumpei Ogura was picked off by Garry Ringrose in only the third minute, leaving the Irish center with an uncontested run to the line.
"It's one of those things," said Japan second-row forward Luke Thompson, who came out of international retirement to make his first appearance since the 2015 World Cup. "It's unfortunate but we didn't go into our shells after that. It's one of those things in rugby."
Ireland scored a second try in the 11th minute when flanker Josh van der Flier touched down in the corner, and although Ogura got Japan on the scoreboard with a penalty soon after, Irish scrum half Keiran Marmion widened the gap with another try in the 17th minute.
But Japan refused to accept defeat and pulled a try back in the 24th minute. Matsushima turned defense into attack with a well-placed kick into Irish territory, and the same player was there to finish off the move after Uwe Helu had punched a hole in the opposition back line.
"I'm in better physical condition than I used to be and I've also gained a lot of confidence in my ability when carrying the ball," said Matsushima. "It gives me even more confidence to be able to do that against a top-three team. It's good experience."
Rhys Ruddock scored again to take Ireland into halftime with a 28-8 lead, and Japan's attempts to hit back after the break were thwarted when Shuhei Matsuhashi was denied a 43rd-minute try after a video replay.
But the home side went on to control the second half and got its reward when Yamada profited from a lucky bounce to touch down in the corner shortly after the hour mark.
"(Rikiya) Matsuda tried to kick it behind their defense but it bounced off one of their players and I got lucky," said Yamada. "We had lots of chances to seize the initiative — more than we would have expected. If we had been able to take one of them, it could have been a better game for us."
A 78th-minute try by Ireland substitute Sean Reidy ended Japan's hopes of making it through the entire second half without conceding a point, but Brave Blossoms flanker Michael Leitch, who regained the captaincy for the game, was satisfied with his team's performance.
"We have learnt things from each game in this series," said Leitch, who returned to the national team for the June series — which also included a 33-21 win over Romania in Kumamoto on June 10 — following a period of rest.
"Against Romania we couldn't see our game plan right through to the finish," Leitch said. "We tried to fix that in the first game against Ireland but there we were lacking mentally. We tried to fix that for today's game and our fighting spirit was there from start to finish.
"Fighting spirit and physicality are the most important things in rugby, and we had them today. We can learn a lot from playing against a team that is ranked in the top three in the world. Ireland never gave up until the end, even in heat like this."
