"With work commitments I don't get to play as many tournaments as I used to so when I do I try and make the most of them," added the Hawke's Bay Hospital nurse who did the best of the Bay women.
Katsu shot rounds of 70, 69, 68 and 70 to finish seven shots ahead of runner-up Mun Chin Keh, of the Titirangi club, who chipped in on the final hole for eagle to claim second place from Japan's Haruka Morita.
Katsu, the Japan No2, is ranked 142 on the world rankings. She said this victory would boost her self belief as she prepared for the Queen Sirikit Cup.
Waikato amateur Luke Toomey delivered on his long-heralded potential when he won the men's title. The New Zealand rep, who began in a share of the lead with Auckland amateurs Tae Koh and Sam An at 10-under par, shot a three-under par 69 in the fine conditions to secure his maiden senior national title by two shots.
Australian amateur champion Koh (71) finished runner-up while Takaka golfer Blair Riordan (70) and An (73), who claimed the Te Mana A Toi trophy for the tournament low round, finished in a share of third place.
Toomey became only the fifth golfer from Waikato to win the St Andrews Salver following Ted McDougall (Tokoroa), Brad Shilton (Te Awamutu), Colin Taylor (Hamilton) and James Gill (Hamilton) and the first champion from the province for seven years.
The 21-year-old from the Riverside Golf Club, who held the third round lead two years ago in the same championship, was proud he showed his renewed maturity to close out the title.
"I am just absolutely stoked to no longer be a bridesmaid and to win this after one of my best friends in Cam [Jones] last year makes it really special," Toomey said.
"I have had that many second and third places I have been wondering when it would be my turn and to open it up at the New Zealand Stroke Play is unbelievable."
Toomey got off to the worst possible start when he made a double bogey on the opening par five when he hit his approach with a three wood out of bounds.
"I made a four foot putt there for double and I took some positives from that into the next few holes."
Toomey brushed off the bad start and made four birdies in a row in what was a tournament-defining stretch where he earned a three-shot lead heading into the back nine. He scrambled hard on the 10th to make par to An's birdie then on the par four 11th he blocked his tee shot right and had to chip out backwards.
The result was a double bogey and all of a sudden An and Toomey were tied at the top.
Host club player Stu Duff was the best of the Bay men and finished 14 shots behind Toomey. His best round was a four under par 68 on Saturday.
