Miyazawa made her third appearance of the football tournament in France as Japan took the favourites United States to extra-time at Parc des Princes, before succumbing to a Trinity Rodman strike in the 109th minute.
The United midfielder was named among the substitutes and came on nine minutes from the end of normal time, when she replaced Manchester City's new signing Aoba Fujino.
With the scoreline still locked at 0-0, Miyazawa twice threatened to put her side in front before Rodman eventually made the breakthrough for Emma Hayes's team.