The 19-year-old from Phuket only joined the Tour as a rookie in March but has quickly become the third Thai to win a Japanese LPGA crown after Ornnarin Satyabanpot and Poranee Chutichai.
Saranporn took home 18 million yen (Bt5 million) for her win out of a total tournament purse of 100 million yen (Bt27.85 million).
She started the final day at the par-72 Katsura Golf Club one stroke behind the leaders and fired 5 birdies to finish on 15 under par and clinch the title by 3 strokes.