World No. 2 Pearly–Thinaah defeated Japan's world No. 7 Rin Iwanaga–Kie Nakanishi 22-20, 21-19 in their seventh final of the year, at the Kumamoto Prefectural Gymnasium.
They had earlier won the Thailand and Arctic Opens.
The Kumamoto victory improved Pearly-Thinaah's head-to-head record against the Japanese pair to 7–2.
Pearly-Thinaah took home US$37,525 (RM155,078) while Iwanaga-Nakanishi settled for US$18,050.
