Irish coach Noel McNamara said that relief and pride were the overriding emotions after his charges staved off relegation to the U-20 World Trophy in France yesterday.
reland had to withstand a spirited rally from Japan before securing their first win of the competition, which is enough to ensure their place in the World Rugby U-20 Championship when it is held in Argentina next year.
McNamara said that it would have been a setback for Irish rugby if they dropped to the second tier for the first time in history.
"We would've dealt with it at the end of the day had we gone down. Obviously, it would've been a setback, particularly for next year's group because this is a fantastic tournament and it's been an amazing experience for these young men," he said.
And he believes that many of this U-20 squad will go on to professional careers with provinces and represent the national senior side, despite finishing 11th in the 12-team competition, their lowest ever finish.
"There are a number of guys who were involved with us in the Six Nations who didn't spend a lot of time with us here who have bright futures ahead of them," he said.
"I think there are some very good players here and I think the future of Irish rugby in the provinces and the national team will be served by this team.
"We knew we were in for a massive battle, it was a cup final in many ways, but an entirely different type of pressure to what most of these young men would've dealt with before.
"So, what can you say about the character at the end, they defended multiple phases and closed out the win. No Irish team has been under this pressure before in this tournament," said McNamara.
Ireland were ahead 22-12 at the break thanks to tries from scrum-half Jonny Stewart, hooker Dan Sheehan and centre Peter Sylvester.
Harry Byrne, who finished with 19 points, tacked on four penalties after the restart, but Japan never gave up and with Tongan-born Siosaia Fifita and the other winger Halatoa Yamasawa both getting their second tries, Japan cut the gap to 34-33 six minutes from time.
However, Tommy O'Brien eased Irish nerves with a try before Ireland had to withstand a 19-phase move from Japan to ensure their place in next year's competition.
Ireland - M Lowry; J Humes, S O'Brien, P Sylvester, T O'Brien; H Byrne, J Stewart (H O'Sullivan 70); J Duggan, D Sheehan (D Tierney 66), J Aungier (J Byrne); C Daly (C Ryan 66), J Dunne; J Daly, M Agnew (J Dunleavy 41), C Doris.
Japan - K Yamasawa; H Vailea, S Vakalahi, Y Mori, S Fifita; H Mamada, A Hondo (S Fujiwara 50),; Y Yamada (G Ishida 53), M Arai, R Tsukayama (S Oyama 53), K Shimokawa, R Hashimoto ; K Yamamoto, H Okayama, A Moala. Ref - Karl Dickson (England).