Japan lost 54-20 to Argentina on Saturday to deny Jamie Joseph a winning start to his reign as Brave Blossoms manager.
Japan, which now heads to Europe to play test matches against Georgia, Wales and Fiji, conceded two first-half tries against 2015 Rugby World Cup semifinalist Argentina before giving up two more early in the second half at Prince Chichibu Memorial Rugby Ground.
Amanaki Lelei Mafi pulled a try back for Japan following a video replay in the 52nd minute, but the world No. 9-ranked Pumas stretched their legs with three more tries before debutant Lomano Lava Lemeki added a late consolation for the home team.
"I'm very proud of the team," said New Zealander Joseph, who represented Japan nine times as a player. "In the first 20 minutes and the last 20 minutes, you saw the kind of attitude that we are looking for in the team.
"It was clear from the start of the game that we had plenty of energy and we wanted to play proper rugby, and we were able to put pressure on Argentina with and without the ball.
"The last 20 minutes, when the game was gone, you also saw the attitude where the players didn't want to give in right until the very end. That last try by Lemeki was a really good sign of what's to come."
Japan went into the game with 13 uncapped players among its 23-man squad, after a series of call-offs that included star fullback Ayumu Goromaru and 2015 World Cup captain Michael Leitch.
"They were very strong, but we never gave up until the end and I think the team will continue to improve from here on," said center Harumichi Tatekawa, who co-captained the team with hooker Shota Horie. "We just need to keep believing in ourselves.
"We played the game at our tempo and managed to score some tries, which was good. We have a lot to things to work on and we want to start looking toward the next game straight away."
Yu Tamura opened the scoring in the sixth minute with a penalty in front of the posts, and Japan showed it would not be intimidated when Lemeki jolted Pumas scrum half Martin Jandajo with a huge early tackle.
But Argentina replied with the first try of the afternoon in the 12th minute when Matias Moroni broke free down the right, and Nicolas Sanchez went on to land two penalties to Tamura's one before Sanchez bagged the visitors' second try of the game.
"I thought the intensity of the game was at a level that we're not used to in the Top League," said Joseph. "Even though we had a lot of passion, we were put under a lot of pressure and made a lot of mistakes and conceded easy tries."
Sanchez added another penalty to give Argentina a 21-6 halftime lead, before Santiago Cordero and Moroni took advantage of some slack Japanese defending to score two quick-fire tries after the restart.
Mafi then grabbed Japan's first try of the Joseph era, after a replay showed the No. 8 touching down amid of heap of bodies on the Argentine line.
Sanchez and Cordero both struck again to stretch Argentina's lead before substitute Tomas Cubelli added another. But Lemeki ensured that Japan would not go quietly when he streaked over the line to touch down in the corner in the final minute.
"Japan always look to play positive rugby and go forward," said Argentina manager Daniel Hourcade, who will now take his team to Europe to face Wales, Scotland and England. "Their team has changed since the World Cup but they still play with that positivity, and the fact that they scored right at the end was down to that.
"When you bring young player into the national team, they play with a strong determination but they can also make mistakes. But you have to do that when you are building toward the 2019 World Cup, and this was a good start for Japan."