Besides the fact they are really disciplined and great fundamentals... I think I touched on the perception they have in their favor for this game. Think about it. Belgium has cruised 5 goals and shit. Then beats England with their fucking B team as a good size underdog.
Meanwhile, Japans only win came from a red card in the 3rd minute vs Colombia. Then a 2-2 draw and then a 0-1 loss where they played terrible and they still got through due to fewer yellow cards( due to their discipline). If that isn’t perception, I don’t know what is