The Black Sticks were on the scoreboard in just the fifth minute when Rachel McCann beat the keeper with a great shot. They were unlucky not to be two up after Kirsten Pearce had a goal disallowed when the umpires ruled the ball had hit a foot on its way into the net.
The second half was punctuated by tenacious defence from both sides.
Japan pushed forward in search of an equaliser and Black Sticks keeper Sally Rutherford was called into action on some occasions.
Rutherford saved two cracking shots that were shoulder height and goal-bound by pushing the ball wide. Then she did enough to scramble the ball clear to avert the danger from a penalty corner.
The match was decided in the Black Sticks' favour when they scored two goals in the 57th minute.
The first went to Tauranga's Rose Keddell who put a reverse stick shot high into the left-hand corner of the Japan goal and then captain Olivia Merry got on the scoresheet when a cross from the left side wasn't dealt with by the Japan defence, and she pushed the ball into the goal.
The Vantage Black Sticks are the first team to win the Hawke's Bay Cup twice in its four-year history.
Black Sticks 3 (Rachel McCann, Rose Keddell, Olivia Merry)
Japan 0. Halftime: Black Sticks 1-0