Defending women's rugby sevens gold medallists Australia made a statement as they opened pool play with a crushing 48-0 defeat of hosts Japan after leading 24-0 at half-time.
Emma Tonegato got three tries while Demi Hayes and debutant Maddison Levi had two each for Australia, who face China later on Thursday.
"I definitely was concerned about this game," said Australia's head coach John Manenti. "Japan, playing at home, it would be very emotional for them and the pressures and expectations could have built on us.
"But I was really pleased with that clinical first half. We could relax at the end of the game and give a few of the girls debuts."
New Zealand, beaten finalists at Rio 2016, began their Tokyo campaign with a 29-7 win over Kenya.