Hataoka offset a pair of bogeys with seven birdies at the Seta Golf Club to finish at 14-under 202, two strokes ahead of compatriots Momoka Ueda, Saki Nagamine and Spain's Carlota Ciganda, who all shot 68.
“I realize something has to come to me and I had to get through it, and I knew it was at the 13th hole,” said Hataoka of the putt that saved her round. “I was not totally comfortable with the shot, but I was calm enough to play well on that hole.”
Ciganda had a chance to tie Hataoka at No. 18 but left her birdie putt from above the hole too short. Hataoka's birdie putt fell, clinching a hard-fought home win.
South Korean golfers Jin Young Ko (66) and Ji-Hee Lee (68) were tied for fifth at 11-under 205.
Lee struggled with her game and had back-to-back bogeys on Nos. 7 and 8 as part of a 78 that left her tied for 15th.
“I didn't hit the shots that I wanted very solid,” Lee said. “So obviously it didn't go the way I wanted.”
The LPGA stop in Japan is the fourth of five consecutive tournaments across Asia. (AP)