There is a buzz about this one. You can just feel it. At the prematch news conferences, in the Loire Valley air, atop the crenelated battlements of the Chateau des ducs de Bretagne, and along the cobblestone streets of Nantes’ Center-Ville.

Something is kindling. And whatever it is, it will come to a crescendo at the Stade de la Beaujoire on Sunday afternoon, when Japan takes on Argentina for a spot in the Rugby World Cup quarterfinals. But until then, we will have to be content to let it simmer.

Japan head coach Jamie Joseph believes World Cups are all about this kind of pressure.

"From what I’ve seen at the World Cup so far, the teams that come out on top are the ones that are able to absorb that pressure,” he said at Friday’s news conference. “The guys are really confident and I’m really confident that if we can create the right pressure at the right times, then we will win this test match.”

Elsewhere in camp, the talk is becoming more adversarial. There is no more space for niceties; it’s out with tatemae and in with honne.

The gloves are off and the knuckles ready.

Japan Team Director Yuichiro Fujii told reporters on Thursday that training had been largely player-driven this week, allowing Japan’s on-field generals to inspire the dressing room.

“(Prop Keita Inagaki) talked about how it’s going to be ‘Samurai Time’ — where once we pull the sword out, it’s going to be do or die — and how we have to drop our katana on them to defeat them,” Fujii said. “Those words about mentality are more important than the gameplan at this point.”

Even the sentiments of the usually stoic captain Kazuki Himeno had the zing of a sword being unsheathed from its scabbard.

“It’s a really big game,” he said. “We want the fans to cheer for the players to push them on. For the players, cheering is power. Not only the national team, but also the whole of Japan must become ‘One Team.’ That is the key to victory in a deadly battle.”

Japan's Kotaro Matsushima evades a tackle from Samoa's Ed Fidow during their World Cup match at the Stadium de Toulouse in Toulouse, France, on Sept. 28.
Japan's Kotaro Matsushima evades a tackle from Samoa's Ed Fidow during their World Cup match at the Stadium de Toulouse in Toulouse, France, on Sept. 28. | AFP-JIJI

Perhaps the players are invigorated by last week’s victory against Samoa. Or maybe Japan’s most-seasoned pros are harnessing the fact that this could be their final game in a World Cup. Because there’s little intimate knowledge for the Brave Blossoms to draw on.

Japan and Argentina are estranged foes — they’ve played only six times in the past 30 years, with the last matchup coming in 2016, a contest Los Pumas won comfortably, 54-20. For the Brave Blossoms’ only victory against Argentina, you have to go back to 1998, a year that predates several of the players set to take the field on Sunday.

Argentina also has a better World Cup record — finishing third in 2007 and fourth in 2015 — and has been bolstered by annual games against New Zealand, South Africa and Australia. Gone are the days when an Argentine victory in the Rugby Championship constituted an upset; it has more than vindicated its place at rugby’s top table.

That said, Argentina came into the competition as many punters’ favorite to top Pool D, but has been underwhelming by its own exacting standards. This suggests it is due for a big performance, and it would be risky to bet against it delivering one.

But even when they’re not growling with their usual ferocity, Los Pumas’ hearts are still stitched firmly onto their blue-and-white sleeves. Passion is their profession. And the clash of the back rows alone is set to take place on the bleeding edge — just look at the cast of characters involved.

Argentina's Pablo Matera (right) attempts to tackle England Alex Mitchell during the Rugby World Cup in Marseille, France, on Sept. 9.
Argentina's Pablo Matera (right) attempts to tackle England Alex Mitchell during the Rugby World Cup in Marseille, France, on Sept. 9. | REUTERs

Pablo Matera, the embodiment of the battle, is a man who always looks like he has gone 12 rounds with Mike Tyson before telling Iron Mike to take another swing if he thinks he’s man enough. With the enforcer Marcos Kremer and the athletic Juan Martin Gonzalez alongside him, Argentina has a trio of warriors you would willingly follow into the pass of Thermopylae.

Japan’s loose forwards will look to match them in this war of attrition. They consist of Japan’s man-of-steel, Pieter Labuschagne; the teary-eyed veteran, Michael Leitch; and the human cannonball, Himeno. These three have captained their country and each epitomizes what it means to wear the Brave Blossoms jersey.

Whoever comes off the better in this domain — that is to say, whoever wins the breakdown — could well be booking a date with Wales in Marseille next week.

The presence of Joseph has been another big talking point in the buildup to the game. After announcing he would step down following the World Cup, Japan vs. Argentina was earmarked as potentially the final afternoon in the hot seat for the country's most successful coach. But on this matter, he was typically self-effacing.

“Argentina was our first match (with me in charge), we’ve just got to make sure it’s not our last match as well,” he said. “Our team has developed well over the last seven seasons. New players have come in, other players have retired, but it’s a really strong nucleus of players that has stayed behind.

“Other than that there’s not really too much more to compare, it’s a new team, led by a new captain. ... We’ve had an up-and-down season but I feel we’re starting to play some of our best rugby.”