"This is probably the best preparation we have had before a World Cup. It has not been done before," she said.
She said all the Kiwis were amping to play tomorrow in their first match against Australia in four years.
"It's exciting. We last played them in 2010 at the last World Cup. We don't really know what they have to offer, but whoever plays the Black Ferns pick up their game.
"And we always want to come out and smash the yellow jersey."
Being a World Cup year, there was a special buzz in the New Zealand camp, she said.
Fa'amausili has been involved in New Zealand's last three world titles and said it never gets tiring winning a World Cup.
"No, it is exciting every year and every year is a challenge to defend our title," she said.
"And we want the girls who have not been there before to have the same feeling - to be on top of the world."
New Zealand have won four World Cups (1998, 2002, 2006, 2010) and are looking to make it five straight in August.
Fa'amausili said one of the special things about this build-up series was family, friends and supporters in New Zealand could come and watch them before going to France.
Black Ferns coach Brian Evans said they were taking this series seriously and wanted to win every match.
"Our first goal is we have to win, that is the non-negotiable for the Black Ferns, and we are in front of our family and friends so that is really important."
He said apart from a few injured players, this was the same squad which would be going to France in August.
He said he was expecting Australia to provide a tough battle tomorrow.
"That is what you want from any Australian sporting team, you know what you are going to be up for. We have only got a few days [to prepare] and that is really important to accept that challenge."
He said the Black Ferns had a few training camps together this year but this would be their first proper international match since July last year, when they played England.
The match tomorrow will be broadcast live on Sky Sport.
The game tomorrow starts at 5.40pm. Tickets are $5 for children and $10 for adults. The curtain-raiser between Rotorua Boys' High School and Tauranga Boys' College will start at 3.40pm.
INTERNATIONAL WOMAN'S RUGBY SERIES:
- Tomorrow: New Zealand v Australia, Rotorua International Stadium (5.40pm).
- Friday, June 6: Australia v Canada, Tauranga Domain (2.30pm).
- Saturday, June 7: New Zealand v Samoa, Eden Park (5pm).
- Tuesday, June 10: New Zealand v Canada, Tauranga Domain (2.30pm).
- Saturday, June 14: New Zealand v Canada, Rugby Park in Whakatane (2.30pm).
