Momoko Ueda became the first Japanese player to win the Mizuno Classic in nine years on Sunday, closing with a 5-under 66 that included a double eagle.
Ueda held off American Reilley Rankin and Sweden's Maria Hjorth to win by two strokes.
"My coach told me to concentrate, instead, on my game and not worry about my opponent," Ueda said. "Today I was continuously thinking about playing good and switched my feeling and I was concentrated like never before. I felt that is how top players might be playing."
She finished at 13-under 203 to earn her first LPGA Tour victory.
"I used to wish for (the) other player to make a mistake. When I was thinking like that, I got nervous whenever they made a good shot," Ueda said.
Hiromi Kobayashi was the last Japanese player to win the Mizuno, taking the 1998 tournament at Musashigaoka.
Ueda came into the final round at the Kinetsu Kashikojima Country Club course tied for the lead with Britain's Laura Davies and took command at No. 7 with the double-eagle, the 28th in LPGA Tour history.
"I could not believe it on the seventh hole," Ueda said. "Whenever I make eagles, my heart beats fast, though I switched and was already thinking about the eighth hole."
Rankin and Hjorth, the 1999 champion, closed with 67s.
"We both played well out there today," Hjorth said. "(Ueda) made the double-eagle out there, which all of a sudden, I'm two shots behind."
Rankin had six birdies against one bogey.
"I gave myself a lot of opportunities," she said. "I don't feel like I lost the tournament; I feel like I made a lot of progress. It was a good experience overall, I learned a lot. I guess that's probably the closest I've been in contention when it comes down to the last day."
Shinobu Moromizato (67) was fourth at 8 under. Davies shot a 72 to tie for fifth at 7 under with Mi Hyun Kim (71), Chie Arimura (70) and Mie Nakata (71).
Davies couldn't recover after being penalized two strokes in the second round for putting from the wrong spot on the 14th hole. She forgot to return her ball to its original spot after moving her mark because it was in a competitor's line.
Japanese star Ai Miyazato continued to struggle, closing with a 75 to finish in a tie for 68th at 8-over 224.