The Blue Samurai, who held the Netherlands to a 2:2 draw in their Group F opener, were always in control against Tunisia at the Monterrey Stadium.
After a tumultuous week in which they suffered a 5-1 defeat by Sweden, sacked Sabri Lamouchi and appointed a new head coach, Herve Renard, it took less than four minutes for Tunisia to go behind in Guadalupe, Mexico.
An impressive Japan, who were well drilled throughout, broke the deadlock with a quick counter-attack which ended in Crystal Palace’s Daichi Kamada prodding home from close range at Monterrey Stadium. The Japanese almost scored again moments later, with only a desperate goal line clearance from Dylan Bronn denying the Asian giants a second goal.
Japan, though, finally added to their tally in the 31st minute, with striker Ueda taking advantage of some hesitant Tunisian defending to surge forward and thunder a low shot into the bottom corner from the edge of the area.
The rout continued in the second half, with Junya Ito latching onto a brilliant through ball to calmly finish on 69 minutes before Ueda scored again with a looping header in the 83rd minute.
