Spain have flown out of the traps in the early stages of this tournament, leading by at least two goals at the half-hour mark in both of their previous group games, but they were on the receiving end of an onslaught in an enthralling first half.
Jorge Vilda's side hadn't learned their lesson, once again caught out on the transition by Japan as Riko Ueki cut in from the left before her shot deflected off the unfortunate Irene Paredes and looped over Misa Rodríguez into the net.
Spain were stunned, but their inability to contain Japan saw them fall three behind before the break thanks to another lightning counter. The two goalscorers combined, as Ueki slotted in Miyazawa to provide another sublime finish to cap off an almost unimaginable start from Futoshi Ikeda's side.
Spain needed a miraculous comeback to rescue the match and their hopes of topping the group, but they were brilliantly neutralised by a resilient Japanese outfit happy to play on the break.
Vilda’s side continued to dominate possession, but they were continually denied a path to goal, failing to register a second-half shot on target before Japan struck again on the counter.
This time it was substitute Mina Tanaka who added a fourth in the closing stages, turning the Spanish rearguard inside-out before firing into the top corner to round off the scoring.
The Nadeshiko have successfully kept all three of their opponents at bay in this WWC so far, winning with an aggregate score of 11-0, signalling their presence as a threat to fellow favourites for the coveted title. They will relish the prospect of a fourth straight knockout stage appearance, where they face Norway next in the last 16.
An unexpectedly heavy defeat provides a real dent to Spain’s confidence, but there’ll be no time for soul searching as they gear up to face Switzerland in the first knockout round.