Reid, 27, closed with an even-par 73 at Carya Golf Club for a four-stroke victory over France's Gwladys Nocera. Reid also won the 2010 tournament at National Golf Club.
Nocera finished with a 71 in the unique Sunday-Wednesday event.
England's Laura Davies tied for third at 6 under with Scots Kylie Walkerand Sally Watson. Davies, 51, finished with a 72. Walker also shot 72, and Watson had a 75.