On Sunday Chris Wyatt will watch his final game in Japan. His 43rd World Cup match since 2011.

Forty three games in three men's tournaments. His favourite one to date?

"The one that I really enjoyed the absolute most was between Georgia and Namibia in Exeter [in 2015]," says Wyatt.

"Namibia nearly got their first World Cup victory, it was 17-16 to Georgia.

"That one kind of stands out for me, it was a great crowd and a great day."

For Wyatt, a Baltimore native who last month concluded 36 and a half years of active duty with the United States Army, the joy of the World Cup is found primarily in experiencing what every team, and their fans, bring to the party.

By the time he leaves Japan he will have seen 18 of the 20 teams at this tournament.

"I only do the pool stage because to me that's much more fascinating," he says.

"You see the minnows, and you never get to see them otherwise. I mean when do I get to see Georgia play?"

Eighteen games in 29 days

Wyatt cuts a restless figure when we meet on platform four of Shin-Yokohama station on the fourth day of the tournament.

Having undertaken the mission of watching 18 games in 29 days, there is little margin for error when it comes to travelling around a country the size of Japan.

It's early afternoon but Wyatt needs everything to run like clockwork if he is to make kick-off between Wales and Georgia some 300km away in Toyota city.

Luckily for him, this is Japan. The train says it's arriving at 14:19, so it does.

Even with the help of a ruthlessly efficient rail network, Wyatt's trip needs to be planned with military precision.

No problem for a man who has spent the best part of four decades planning things to that end.

In a career that saw him travel the globe several times over, Wyatt spent much of his time in Africa as a Foreign Area Officer and served as the Director of African Studies for the US Army War College.

Although his love affair with rugby union began as a college freshman in 1982, it was not until a conversation with an Australian colleague in Liberia 25 years later that the idea of travelling to a World Cup began to take shape.

When watching South Africa defeat England in the 2007 showpiece, a plan to meet at the tournament in New Zealand in four years' time was agreed.

Maximising the World Cup experience

And so to 2011, where fortuitous circumstances allowed Wyatt to take the short notice leave required to turn his World Cup pipe dream into a reality.

Upon arrival and with no tickets, Wyatt used the situation as a blank canvas to formulate the process that he still uses when working out his World Cup roadmap.

"I drove into Auckland and looked at where I could go," he explained.

"There was one in Hamilton, Wales against Samoa, so I drove down there and wound up buying a ticket from a guy. Six rows up, centre of the pitch.

"That night I got a hotel room. I didn't have any other matches booked so I went online and I made a plan."

The plan was based not on the best rugby, but on the best experience.

"What's feasible, what can I do to see the country and learn something about it?" Wyatt said.

"Springboks games are a priority, then USA games and then any other team I can see."

The fans make the tournament

Since 2011 there have been five World Cups, three men's and two women's, Wyatt has been to every one with each trip becoming more ambitious than the last.

His 18-game trip to Japan is his most ambitious yet and by the close of Sunday's group stage he will have travelled to nine of the 12 venues and watched every team barring the hosts and Argentina.

Missing out on seeing Japan in front of their own fans is a shame. The Brave Blossoms have so far lit up the tournament with their exhilarating brand of rugby matching the atmosphere created by the home fans.

Thankfully though, the presence of local fans has been a fixture of every game so far, something that Wyatt argues is the key to a successful World Cup.

"The most important thing to a World Cup is the fans," he says.

"Japanese fans are top drawer. You can't have empty stadiums, and you can't have people that are just there to be drunk or people who are clueless."

True to form, the stand-out moments for Wyatt have so far arrived not on the biggest stages in Yokohama or Tokyo, but in some of Japan's lesser known areas that have risen to the challenge of opening their doors to the world's rugby fans.

"When I got to Kumagaya, from the moment I got off the train there were volunteers everywhere.

"You walk down the street and there are people offering you high-fives and pointing you towards the stadium.

"There were school groups all over the stadium and it really added a nice touch.

"When it comes to a World Cup it comes down to the organisers and the quality of the volunteers."

Wyatt's tournament ends on Sunday with the USA v Tonga.

Perhaps not the encounter that most onlookers are focusing on as the pool stage reaches its crescendo.

But, for Chris Wyatt, game number 43 is exactly the type of fixture that will see him travelling the globe to attend more World Cups for many years to come.