Japan's surprise advance to the World Cup knockout stage has turned Emperor Akihito and Empress Michiko into football fans who even woke before dawn to watch live TV coverage.

The news emerged when the royal couple received Japan's coach Takeshi Okada, two senior players and the president of the Japan Football Association Motoaki Inukai at the Imperial Palace.

The Blue Samurai defied their underdog tag to progress from the group stage after beating Cameroon 1-0, losing by the same margin to the Dutch before stunning Denmark 3-1.

Their dream of reaching the World Cup quarter-finals for the first time was thwarted by Paraguay who beat them 5-3 on penalties after a goalless draw.

"I was very much moved when I learned that their majesties had seen almost all of our matches live," Japan captain and Wolfsburg midfielder Makoto Hasebe told reporters after the audience.

Coach Okada said that Empress Michiko, one year younger than the emperor at 75, told him that she got up to watch the Japan-Denmark game which started at 3:30 am Japan time.

"When she woke up so early in the morning, his majesty was also awake. They agreed that they would watch television together," Okada said.

"Their majesties told us that the team had fought as one as Japanese," said the 53-year-old coach whose reputation has soared from rock bottom since his squad lost four straight pre-World Cup internationals.

"I feel glad that their majesties were very open and showed a great interest in football."

In their rare public appearances, Akihito and other members of the Imperial Family have often watched sumo bouts and baseball games, while football lagged behind those sports in popularity.

The royal couple invited the country's national football team to the palace before the 2002 and 2006 World Cups.