"It was a tough match in hot conditions but I thought both sides played at a high tempo and we are pleased to come away with the result," Smith said.
"We are looking forward to continuing the challenge in Hamilton next week. This series is a fantastic opportunity to progress ahead of a very busy year."
After a high tempo opening quarter the Kiwis took the advantage when captain Blair Tarrant slipped a great ball into the circle for Marcus Child who tapped in past the goalkeeper.
Child scored his second goal of the match in the 25th minute after swooping on a penalty corner deflection and hitting home.
With New Zealand in control at halftime, Japan pulled a goal back immediately after the break when Shota Yamada sent a penalty corner flick into the cage.
Just a minute later it was a highlight reel moment for the Black Sticks when Marcus Child sent a long sideline overhead into the circle for Dominic Newman to showcase some brilliant skills and fire a bouncing ball past the goalkeeper.
Japan mounted an incredible comeback after the New Zealand goal, scoring three times through Hirotaka Zendana, Tsubasa Yamamizu and Koji Yamasaki to take the lead.
But the Black Sticks equalised through a 55th minute penalty corner flick from Kane Russell before a stunning effort saw Hugo Inglis net just two minutes from the final whistle.
In the Four Nations final, Belgium held on under huge late pressure to defeat India 2-1 in a top quality clash.
Belgium scored a goal in each half with a Tom Boon penalty corner and Sebastien Dockier field goal, while India's lone goal came from Mandeep Singh in the 19th minute.
With the Tauranga leg of the University of Waikato Four Nations now decided, teams head to Gallagher Hockey Centre in Hamilton for the next series from January 24-28.
The first day's action in Hamilton will see Belgium play Japan at 5.45pm before the Vantage Black Sticks meet India at 7.30pm.
FINALS DAY RESULTS - BLAKE PARK, TAURANGA
Vantage Black Sticks: 5 (Marcus Child 2, Dominic Newman, Kane Russell, Hugo Inglis)
Japan: 4 (Shota Yamada, Hirotaka Zendana, Tsubasa Yamamizu, Koji Yamasaki)
Halftime: Vantage Black Sticks 2-0
Belgium: 2 (Tom Boon, Sebastien Dockier)
India: 1 (Mandeep Singh)
Halftime: 1-1