TOKYO, 4 Oct - Japan have not only pulled off the biggest upset of Rugby World Cup 2019 so far with their 19-12 victory over Ireland, they also boast its most lung-busting statistics.

The Brave Blossoms have made the second-most tackles among teams who have played twice, and their tackle success rate (90 per cent) is the second highest. Only Ireland (92 per cent) have completed a higher proportion.

So far, Japan have made 149 carries per match, higher than anybody bar Australia (156), and have averaged 578m gained, which has been beaten by only three teams (England, New Zealand and Italy).

Among the tournament's stand-out individuals, 33-year-old hooker Shota Horie is joint third overall for tackles (35), with a 97 per cent success rate, while flanker Pieter Labuschagne and second-row James Moore are joint fourth (34), with 92 per cent. Of all players after two matches, back-row Kazuki Himeno is second for total runs made (33), one behind Australia's Samu Kerevi and level with New Zealand's Beauden Barrett and the Wallabies skipper Michael Hooper. 

The Japan players, pictured above, were able to overpower Ireland, then ranked world No.2, thanks to relentless pressure and boundless energy. But where did this superior physical fitness come from? 

One man is largely responsible. New Zealander Simon Jones, the team's strength and conditioning coach, was brought into the set-up in 2016. He left a post with the Southern Steel netball team, having previously worked with the All Blacks U20s as strength and conditioning manager for high performance sport in New Zealand.

The secret to Japan's fitness regime remains under lock and key, but the players have indicated their sessions are even tougher than the brutal methods adopted by former head coach Eddie Jones in the build-up to Rugby World Cup 2015.

Under Eddie Jones, the squad spent a total of 75 days across 10 training camps on Kyushu off the Pacific coast of Miyazaki, complete with dawn starts and dusk finishes.

"Those training camps were hard, very, very hard," said Rich Freeman, rugby correspondent for Kyodo News, who has been tracking the Brave Blossoms' ascent up the world rankings. "Eddie knew how far he could push them. The players were up at 5am and wouldn't crash out until gone 9pm."

Freeman believes no other team would have accepted what Jones put them through but that Japanese players have grown up with an after-school club system called kurabu katsudo, or bukatsu for short, which instils discipline and a dedicated work ethic. 

Whichever sport or activity they choose, youngsters stick with it for 350 days a year. In summer they can practise for eight hours a day. "That's what they have been brought up with and that's what Eddie gave them at international level," Freeman said.

This year, with Simon Jones on board and Eddie inflicting those sessions on England players instead, Japan revisited Miyazaki for 19 days in June and 17 days in July, but also travelled north, spending 10 days in Abashiri on the eastern tip of the island of Hokkaido. In that cooler climate, the squad was able to train at high intensity for longer than would be possible in Miyazaki and, as Ireland will no doubt testify, it appears to have lifted their fitness to a new level epitomised by hooker Horie, pictured.

"We've built things up from Miyazaki in terms of fitness," try-scorer Kenki Fukuoka said. "We could continue that hard defence without losing our physicality. We kept producing double tackles without letting them come to us. The long period we have had in preparation has been huge."

Fly-half Rikiya Matsuda said the work put in by the team had emboldened them: "That is giving us the belief that we don't lose."

Second-row James Moore agreed that they had been working on their physicality, especially in defence, for a long time. 

"This year it stepped up to a whole other level at Miyazaki camps and Abashiri, and I think we really showed our physicality at the Pacific Nations Cup, and the start of the World Cup."

RNS sr/pp/co/sw