Actually, the Japan team was already out of stamania at that time, that's why they let Belgium score 2 goal easily and with a team in Asia that made their all effort to score 2-0 at first against Belgium, it took them a lot of energy so they have to try to end a match in 90 minutes. If they was be able to hold the match to an extra time, they would still lose to Belgium, even lose of a very big gap of conceded goal.That 2018 Belgium match would always be weird to me. I could never understand why almost all outfield players of Japan went into the box for a last minute corner against significantly taller opponents then got countered.
Even if they didn't get much stamina left, going to extra time then defending for the shootout is much better choice.