Japan team-mates went together to school and signed the World Cup promise in yearbook.

Kaoru Mioma and Japan teammate Ao Tanaka went school together, dreaming of playing at the World Cup. Japan could reach quarter-finals if they beat Croatia

The pair were boyhood friends at Saginuma Elementary School in Kawasaki, the city famous for producing high-powered motorbikes. And when they combined in spectacular fashion for the goal that shocked Spain, sent Germany skidding out of the World Cup and took Japan roaring into the last 16, they fulfilled a promise they once made to their old school.

The following summer, Tanaka repeated his pal’s words. So when Mitoma managed to keep the ball going out of play by the tightest of margins to send in a cross that Tanaka was able to bundle home, their joy was made even sweeter by the knowledge that they had fulfilled their childhood vow.

“That was why when everyone thought the ball would go out of play, I believed in Mitoma. I knew he would run to the end. That was what ultimately led to the goal. It was because I believed in him. We played football together when we were small and now we are together on the biggest stage."

Japan beat both Spain and Germany to top their group - and it will take another monumental effort for them to continue their odyssey when they face 2018 World Cup finalists Croatia. Japan defender Yuto Nagatomo has told his teammates they'll need to show “samurai spirit" in Monday's round-of-16 match against Croatia at the World Cup.

And they'll need another quality that Nagatomo learned playing for almost a decade in Italy, mostly with Inter Milan. “Coraggio," Nagatomo said. “We need to play with courage." Japan are appearing in the knockout stage for the fourth time and still searching for their first win. They rallied in group play to beat Germany and Spain — two former world champions — 2-1 but also stumbled to a 1-0 loss against Costa Rica.

Croatia, the smallest country in the final 16 with a population of only 4 million, were the runners-up four-and-a-half years ago against France and finished third in 1998. Could the third time be the charm? “Why not," said Croatia coach Zlatko Dalic.

“I have never forgotten," Nagatomo said, before returning to the subject of Japanese samurai warriors as a metaphor for Japan’s World Cup campaign. “They try to improve their techniques," he said. “But if they are scared during the battle, they will not be able to use their weapons and techniques fully."

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