Bo-Mee Lee needed six playoff holes on Sunday to win the LPGA Championship Konica Minolta Cup.
Lee and Mamiko Higa carded 4-under 68s to end at 11-under-par 201 at Eniwa Country Club.
The final round was washed out by bad weather and thunderstorms, but there was enough of a window to get the playoff in.
The pair matched scores for the first five extra holes, before Higa found water on the sixth playoff hole. That opened the door for Lee to seal the win.
Yuri Fudoh also shot 68 in the third round to end alone in third at 7-under 205. Erina Hara managed a closing 71 to grab fourth at minus-6.