Japan pushed Ireland all the way yesterday, but the young Greens held out in France to avoid the humiliation of being relegated from the World Rugby U20 Championships.
Facing last year’s World Trophy winners - the second tier competition at this age-group on a global level - the Irish finally won their only game of the championships to finish 11th overall after a 39-33 success.
Japan out scored Ireland by five tries to four but the boot of Harry Byrne was enough for Ireland to avoid making the drop to the World Trophy next season.
Ireland played against the strong breeze in the opening half and turned around at the interval leading by 22-12 after starting and finishing the half well.
Ireland, with captain Caelan Doris leading the way, got on top early on and hit the front after five minutes when scrum-half Jonny Stewart crossed.
Byrne added the extras and a good lineout delivered a second try after eleven minutes when Doris fed his hooker Dan Sheehan to bulldoze over in the left corner.
But the handling errors which were rampant in their four defeats prior to this manifested themselves again in a game played in front of a couple of hundred supporters on the back pitch at Stade de la Meditterranee in Beziers.
Japan, so unlucky to lose to a late Georgia try on Tuesday, hit back and winger Halatoa Vailea got over for a converted try after 15 minutes.
They tied the game eight minutes later when a good lineout drive was eventually finished by tighthead Rento Tsukayama to leave it 12-12.
However, Ireland finished the half strongly. Byrne kicked a penalty after a superb break by Doris and then a 20-phase move six minutes from the interval was finished by Peter Sylvester to lead by 22-12 at the break.
Ireland pushed on after the restart with three penalties in the opening ten minutes of the second-half from Byrne to increase their lead to 31-12.
Japan hit back and their huge Tongan-born winger Siosaia Fifita got in for a converted try to cut the gap to 31-19 after 56 minutes.
A nervous final quarter looked on the cards when Fifita got in for his second try in three minutes after poor Irish tackling to leave it 31-26.
Byrne eased the Irish nerves with another penalty after good work by the Irish pack.
But once more Japan hit back and Vailea got in for his second try six minutes from time, with Yuto Mori’s fourth conversion cutting the gap to 34-33.
However, Ireland responded superbly and Tommy O’Brien sealed the win with an excellent try in the left corner although Byrne’s missed conversion ensued a nervous finale to Ireland’s championship.
Meanwhile, England were beaten in the final of the Under-20 Championship for the second successive year following a 33-25 loss to France.
Fly-half Louis Carbonel kicked seven penalties and a conversion to lead the hosts to victory in Beziers, backed up by tries from Cameron Woki and Adrien Seguret.
England, beaten by New Zealand at this stage in 2017, were outplayed for much of the match but gave themselves hope through two Jordan Olowofela scores and another from Joe Heyes, adding to a couple of penalties from Marcus Smith.
It was the first outright success for the French - who topped Ireland’s group - at this level.
South Africa - who were runners-up in Ireland’s group - produced a surprise result in the Third Place play-off as they defeated New Zealand 42-30.
The result of the tournament will go to Georgia, who defeated Ireland in the group stages and then finished ninth with a win over Scotland on Sunday.