A year ago, Hideki Matsuyama also pulled out of a tournament just weeks before the start of the Masters when he was the defending champion.
Jin Young Ko wins the tournament by two strokes over Nelly Korda, with Ayaka Furue and two others one shot further back in Singapore.
The 29-year-old Scot beat Kana Nagai by four strokes for her first LPGA Tour title, while overnight leader Momoko Ueda tied for fifth at 12-under 276.
The two-time winner of the tournament birdied the final hole of the third round to remain on top. Gemma Dryburgh is one shot off the pace.
The 2007 and 2011 tournament winner has a one-stroke advantage over compatriots Ai Suzuki and Miyuu Yamashita.
Ai Suzuki, the 2019 tournament champion, and Momoko Ueda carded 7-under 65s to finish one stroke ahead of compatriots Ayaka Furue and Sakura Koiwai.
The American made a clutch birdie on No. 17 to take a two-stroke lead to the final hole at the Accordia Golf Narashino Country Club.
The American, who has roots in Japan, was steady throughout and came up big on the final hole.
The former world No. 1 amateur is alone in fifth place after a spectacular 63 at the Accordia Golf Narashino Country Club.
The defending champion will need a strong round to get back into contention as he bids to become the first two-time winner of the tournament.
The Kobe native finished two shots off the pace after entering the final round in a three-way tie for the tournament lead in Portland, Oregon.
The 19-year-old became the youngest winner of the JLPGA Championship Konica Minolta Cup, earning the title with an 8-under 64 in the final round.
