It's a whole new ball game in the bars of Roppongi

"What a start, eh?" said the man at the urinal in the Frog and Toad in Roppongi. "What a start! France down. Down to Senegal!" He paused as he rezipped. "That's what it's all about."

One does not often have this sort of conversation in Japan, but then this is a remarkable weekend for Tokyo. Yesterday alone, between 2,000 and 3,000 England fans landed in Japan to join the 1,600 who had arrived already. So did large contingents of Irish, Swedes and Italians. Last night, as France met what might prove their Waterloo in South Korea, a good proportion of them were out in the bars of Roppongi.

Those visiting Japan for the first time must have a strange impression of the city, for in the past few days Roppongi has come to resemble a police state. In the stretch of road between the big crossing and the Frog and Toad, there were hundred of police gravely patrolling in groups of eight and ten. Coaches with mesh over the windows and a dozen blue vans lurked around the corner. But if anybody had noticed in the Frog – and in Paddy Foley's, the Irish pub next door – nobody was paying much attention.

"Japan is amazing," said Stuart Fraser, a 29-year old account manager from Wimbledon who was drinking with a friend. "I only got here a few hours ago, but the transportation system is so efficient. And people are so friendly. I'm really enjoying the culture."

As an English pub, the Frog and Toad is not widely recognised as a repository of Japanese culture, but two of its female representatives were already deep in conversation with Stuart and his friend.

"It's the interaction between the fans and the locals which makes an event like this," Stuart explained. "And Japanese girls are gorgeous."

Roppongi is traditionally the place where such cultural interactions take place – a square mile containing hundreds of establishments, sleazy and respectable. The hostess bars and strip joints, by and large, are the preserve of Japanese salarymen; the bars and pubs are the meeting place of foreign men and young Japanese women. To respectable Japanese, the prospect of a few thousand football fans added to this mix is nightmarish. But in the Frog and Toad, at least, everyone was having a good time.

Most Japanese have only two images of international football. The first is of their own domestic spectators, who arrive at the ground early, patiently queue, politely shout and applaud at appropriate moments, and tidy up their litter before quietly going home. The other is of hooligans who ran riot in Charleville at the previous World Cup in France, caught on a video that has been replayed over and over here. The idea of something in between – noisy, but peaceful – is something that they have never seen.

I watched the France v Senegal match in a bar with a good Japanese friend, a well-travelled and well-educated woman with many foreign acquaintances.

"Do they always do that, or is it just for the last game?" she asked, when the cheering for Senegal began at the final whistle. I had to explain that she hadn't seen anything yet.

For all their good spirits, Japanese trepidation about the tournament had not gone unnoticed by many of the fans.

Stuart Fraser said: "At the airport I was interviewed three times by different Japanese TV programmes, and they all asked what I thought about hooligans. They're so hyped up about it. I said that we are ambassadors for our country and we're only here to have a good time."

All spoke of long queues at immigration, and suspicious questions for those who had arrived by unconventional routes.

Some of these were very unconventional indeed. Paul Dubberley of West Bromwich had spent two and half months travelling overland by public transport – trains, buses and taxis, through Europe, Iran, Afghanistan, Pakistan and China. He was drinking on the street with Daniel and Olof, a pair of Swedes who had taken the trans-Siberian railway – the three had become friends on the boat from Shanghai to Osaka.

"I've been here for four days, and everybody is just getting on," said Paul. "I learnt that in Iran. The government says, 'Death to America', and our government hates their government, but ordinary people are just as nice everywhere."

But there is no getting round the expense of the journey and the city. Even in the plastic glasses the Frog and Toad is using for safety reasons, beer is 900 yen or £5 a pint. No one I spoke to was expecting the round trip to cost much less than £2,000. Justin Hodge of Kent was paying that, for just five days – after tomorrow's match between England and Sweden, he will fly home to Kent. "But when else in your life are you going to do the two things?" he said. "See the World Cup and see Japan. Look around – we're in Japan. We're in Japan, and it's fantastic."