The 12 "Power Rangers" in green jumpsuits with white socks and green sock-like headgear are delighted. The Irish fans dressed in Japanese Kendo martial arts suits and Arabic dress are over the moon. The costumes can all be brought over to Korea now that the Republic has qualified for the next round.
The fans didn't just go to watch a match in Yokohama, they went to put on a show.
"It's a kiddies' suit, it comes in one piece, we bought them in downtown Tokyo," says Lee, one of the Power Rangers supporters who was a little too embarrassed to give his last name.
Brian Mason, in full Arabic head-dress and an improvised gown which looks like two sheets sown together, is in no doubt that he has made the right choice by booking ahead for Korea. "We knew we'd get through. How could we not go on all the way?" says the recently-graduated DCU student from Donnybrook in Dublin.
He and friend John Reddy from Sandymount have been camping around Japan and say they have spent less than €100 on accommodation. "Its been great, it's worth sleeping rough," John Reddy says.
Japanese fans came out in droves to support the Irish team and also showed that they were not afraid to go a bit mad. Bright green afro wigs, faces painted in the Irish colours and T-shirts bearing the name "Keane" were everywhere. Some walked with huge Irish flags draped over the shoulders with the signatures of fans scrawled all over.
"I saw the Germany-Ireland game and fell In love with Ireland," says Hirano Yoshinori.
The supporters of Saudi Arabia showed that they, too, could attract the natives. Outside Shin-Yokohama station, where the stadium is located, a Saudi music group put on a dance routine, attracting applause from everyone.
"Fáilte go Yokohama," says a local schoolgirl who was handing out paper trinkets in the colours of the Irish flag to fans.
Not all can make it on to the next stage, however. Ian Hough, now living in Manchester but originally from Mayo, flew out to Tokyo on Sunday and returns home today. "I came out for one game on the spur of the moment and am delighted I did. I got a ticket in Roppongi for about €250 and would have paid even more to be here," he says.
"We've had nothing but wonderful memories," says Brendan Hughes from Galway. "The people here have been wonderful, the support from the fans has been wonderful, but it's time to go home."