The unpredictability of the Swedish team would be the key to victory.
And Blue and Yellow shocked Japan immediately.
Sweden got off to a dream start when they struck after just seven minutes of play.
Fridolina Rolfö did attempt a finish, but from an awkward position, sending the ball into the away fans.
Punished Sweden
The yellow-clad intense starts continued and they made it difficult for Japan.
But the home nation gradually grew into the match and in advance, the Swedish national team stars had raised a warning finger for their playing skills.
There was a reason.
With 23 minutes played, Japan put themselves up 0 - 1 after an attack from the right, caused by a defensive blunder.
Amanda Ilestedt fell behind and Mina Tanaka, who ran in behind, easily put in the equalizer.
Many probably put their hearts in their throats when the referee blew a penalty for Japan ten minutes later after Tanaka easily fell in the penalty area.
Too easy, it turned out.
After VAR review, the judge changed his decision and the penalty was removed.
Equally good start on others
Japan then continued to impress in the second half.
But it was Sweden who would receive a dividend in the 53rd minute.
Stina Blackstenius was served by Fridolina Rolfö and the BK Häcken striker thundered in his fourth goal in the tournament.
The Swedes in the driver's seat - again.
With 68 minutes played, the visitors broke through on the right after some poor defending.
That time in Sweden's favor - and the referee chose to blow for the penalty kick.
It took 32-year-old Kosovar Asllani and she coolly set her 39th national team goal.
The goal changed the match picture and in the final minutes Sweden had good control.
The team took care of the defensive and replaced players that Hanna Bennison came in with important energy.
Sweden will face Tony Gustavsson's Australia in the semifinals, a national team that Blågult beat 4-2 in the group stage.