Reigning champions have a huge following at this World Cup but not that many of them are from New Zealand • We are expanding our coverage of New Zealand. Please help us by supporting our independent journalism

Three hours before kick‑off, the little square outside Tobitakyu station was already overflowing with New Zealand fans, spilling out down the road towards Tokyo Stadium. The ground holds 50,000 and by the time it was full you could see at least three-quarters of them were wearing black, mainly branded All Blacks swag. Jerseys, jackets, caps and flags. It didn’t matter that most of them have never even been to New Zealand. It’s been like this at every game the All Blacks have played. They had the best part of 65,000 at Yokohama, almost 40,000 at Oita, where they were packed so tight around the front gate that the jam made the buses late.

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In Tokyo the crowd was so thick there were policemen with bullhorns on every corner urging you to “please stay close to the person in front of you and keep moving”, but I latched on to one bewildered New Zealander who had stopped in a far corner. His name was Dave Ward and he had just got in from Wellington. “Jeez, it’s like a home match,” Ward said. “I got to the station and it was like a sea of black in front of me. I’ve never seen so many New Zealand fans.”

Ward shouldn’t have been so surprised. The All Blacks have spent years building their brand in Japan. That match against Namibia was the fifth Test they’ve played here in the last year, and the seventh in the last decade. They have got commercial partnerships with two Japanese firms, Nissui and Mitsui Fudosan, and two of their main sponsors, AIG and Adidas, have been running expensive PR campaigns here, too. AIG’s advert, in which the All Blacks hare around Tokyo tackling people out of the way of crashes and accidents, is running on a loop on the little TV screens fixed in the subway trains.

The All Blacks first toured Japan in 1987 but the game everyone remembers was in 1995, when the two teams played each other at Bloemfontein in the World Cup. The All Blacks won 145-17, which is still the record for the most points ever scored in a Test. In Sapporo, I met Len Schinkel who is half Japanese, half New Zealander, and spent his childhood moving between the two countries. “Rugby used to be big here,” he said, “but when we lost to New Zealand so badly in the 1990s everyone stopped watching. They only started again when we beat South Africa in 2015.”

Facebook Twitter Pinterest Japan’s head coach Jamie Joseph is a former All Black who also played for Japan at the 1999 World Cup. Photograph: Charly Triballeau/AFP/Getty Images

The man who captained Japan in that match, Masahiro Kunda, thinks of it as a noble failure. The reason Japan lost so badly, he’s said, was because he told the team “no matter how many points we concede let’s go and score a try”. That strategy didn’t work too well, so four years later Japan had a different one.

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There hadn’t been a single New Zealand-born player in the team they took to the 1995 World Cup – for the 1999 tournament they had five of them, including the former All Blacks Graham Bachop and Jamie Joseph, who is now their coach.

It wasn’t just the national team. A lot of the top schools arranged exchange schemes, too, and kids from New Zealand started coming over to study here for a year abroad. Some, such as Michael Leitch, ended up staying. Established Japanese players started going back the other way, such as the scrum-half Fumiaki Tunaka, who played for Otago and then Highlanders, and his back‑up, Kaito Shigeno, who spent 2015 playing for Ponsonby and Auckland.

The last thing New Zealand needs is more players, but, on the other hand, they do want more fans. There are only 4.75 million people in New Zealand and they have already made fans of most of them. According to the NZRU’s annual report it put a “special focus” on marketing in Japan last year, turning out Japanese language posts on social media and sending Steve Hansen, and other All Black grandees, on special visits to the country during the summer. Whatever that cost, it will have been offset by the $1m fee the little city of Kashiwa paid for the right to host their training camp for four days.

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It’s not just about money. The NZRU has been encouraging its players to come up here, too. Not just old stars – though Dan Carter is playing in Kobe – but squad players. Guys such as 31-year-old flanker Matt Todd, who might otherwise be weighing up offers from clubs in Europe. The short Japanese season means they can get back in time to play Super Rugby. The NZRU’s head of professional rugby recently described it as the “lesser of two evils”, since the alternative is losing them for good.

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Akio Ohisi, one of those Japanese All Black fans outside the ground, says this means “we’re already familiar with many of the All Black players from the Top League, but we don’t know the Europeans, because we rarely get to see them”. But then the Top League pulls in crowds of only about 5,000 and a lot of the other people here are what Ohisi calls “niwaka” fans – newbies attracted by the All Blacks’ cachet.

You can find plenty of that down at the Adidas store in central Tokyo, where they are running an All Blacks-themed art exhibition with works by Noritake Kinashi, huge swirling psychedelic designs inspired by the All Blacks’ “playful creativity”. Those aren’t necessarily the first words that come to mind when you think of, say, Colin “Pinetree” Meads, but still, inside, the queues for one of the All Blacks’ limited-edition bomber jackets is so long it’s doubling back on itself.

Out front there were a couple of young kids shouting at the passing out-of-towners. “Hey All Blacks!” they say in what seems to be their only piece of English. “All Blacks! Very cool!”