“We’ve got a goal to make the top eight and we’re not there yet,” said the lock Luke Thompson. “We know that in 2015 we won three games and still missed out. That hangs in the background but we are a new team and we still know the challenges we have.” Thompson was no lone voice in a wilderness of celebration. Team captain Michael Leitch wore the expression yesterday of a man turning up at a funeral as he addressed the media the morning after the game and scrum-half Fumiaki Tanaka had his game face on afterwards too.

They all did.

The squad has sworn off alcohol for the tournament, although Thompson might have broken ranks with his mad talk of a quiet one after the game, and Tanaka echoed what so many of his teammates said when describing this as a beginning rather than an end in itself.

They’ve been here before, heralded by their countrymen and women and by the sporting world at large for their defeat of the Springboks in Brighton, and yet memories of that game have clearly been soured by their failure to break through to the last eight.

“Finally, we’ll be freed from the South Africa talk,” said Tanaka. “We’ve been through that all the time for the past four years. I want to say, it’s not just South Africa, and we showed the kids if you put effort in you can beat anyone.” This is all admirable. Essential, even. Japan can’t afford to dwell on this, but we can.

When Tanaka made his debut for Japan in 2008 a team by the name of the Arabian Gulf provided the opposition. Thompson’s first game in the red-and-white was a year earlier when Hong Kong were in the other dressing-room. Different times.

That latter game was played at the Prince Chichibu Memorial Stadium in Tokyo, the game’s spiritual home in this country, which is now closed and due to be relocated. The big Kiwi was the only player on the 22 not born in Japan but 12 of the 23 on Saturday were born offshore.

They have adapted. They had. The progress made by Japan in Thompson’s time has been extraordinary. His first taste of a World Cup came in 2007 when they shipped 91 points to Australia and 72 to Wales. The high point of that campaign was a 12-12 draw with Canada in Bordeaux.

They were deemed to be 21-point outsiders against Ireland here which was understandable in the context that they had lost all seven of their previous meetings by an average of 31 points, but a different stat stands out now that history has been made.

This 19-12 win was Japan’s fifth victory in their last six World Cup fixtures and this after they won just one of their first 24 games across their previous tournament appearances. They are clearly a coming team at this elite level.

“Everyone had written us off,” said Thompson. “All the Irish media were talking about South Africa and how they are going to play them in the quarter-finals and what they have to do. So we know what we have to do. It’s a very special moment.” Japan had talked big all week. There was a matter-of-fact conviction in their voices as they spoke about the chances the Irish defence gave you out wide and their intention to neutralise the big Irish pack with two tacklers at a time.

That same bald clarity was there in the aftermath too. The winger Kotaro Matsushima spoke of an Irish attack that wasn’t “fearsome at all” and it was the converted prop Isileli Nakajima who summed up just how comprehensive a win this really was.

“We beat them better than the Springboks,” he said.”So it’s awesome.”