Coach Hajime Moriyasu cautioned it was only a friendly, but Japan's slice of history with a statement 1-0 win over England at Wembley shows they could go deep at the World Cup.
Japan strolled through Asian qualifying to become the first team to seal their place at the finals in North America and beat Brazil 3-2 in a friendly at home in October.
On Tuesday, they faced England, who like Brazil, are among the favourites to win the showpiece this summer, and were full value for their victory.
Kaoru Mitoma's composed finish in the first half at Wembley condemned England to their first defeat by an Asian nation.
Moriyasu has said that Japan want to win the 2026 World Cup, and on this evidence, that does not seem quite so outlandish.
But Moriyasu struck a note of caution, especially with Thomas Tuchel's England missing the influential trio Harry Kane, Declan Rice and Bukayo Saka.
"Coming to the World Cup, I know it will be a totally different team for England," said the coach, whose side beat Scotland 1-0 on Saturday in Glasgow.
"Also, for us, this game at the end of the day is just a friendly game, so we must keep that in mind as well."
Japan, Asia's highest-ranked side at 18 in the world, are in a testing group with the Netherlands, Sweden and Tunisia this summer.
But they should have more than enough to make it through, as they attempt to go beyond the World Cup last 16 for the first time.
SURGING CONFIDENCE
At Qatar 2022, Japan beat Spain and Germany in the group phase, before losing on penalties to Croatia in the knockout rounds.
They look well-equipped to go further this time with a squad full of technically gifted players who ply their trade in Europe's top leagues.
Wembley match-winner Mitoma, of Brighton, is one of the best wingers in the Premier League on his day.
Japan also have Premier League pedigree in Crystal Palace midfielder Daichi Kamada and Leeds midfielder Ao Tanaka.
Takefusa Kubo did not feature in the recent friendlies because of injury, but the 24-year-old Real Sociedad attacker is well established in Spain's top flight.
Going back to 2019, he has 29 goals and 21 assists in 213 LaLiga games.
In goal, Moriyasu kept faith in young stopper Zion Suzuki after a shaky start to his international career.
Now 23, the New Jersey-born goalkeeper, whose father is Ghanaian, has been linked with a move to the Premier League because of his good form for Parma in Italy's Serie A.
Following the England victory, Moriyasu again said that winning the World Cup was the goal.
Moriyasu has his side finely tuned and they know exactly what to expect from him, having been in charge since 2018.
"I'm confident that we can win no matter who we face," he said.