In the first all-Japanese WTA final in 22 years, Doi made the better start and twice broke Hibino's serve in the first set.
But Hibino ran off nine straight games to take command of the final, as Doi grew more erratic.
Doi racked up 14 unforced errors in the first set, to just eight winners, and was broken in six consecutive service games to fall behind 6-3, 4-0.
Doi regained some late momentum by winning consecutive games and breaking serve for a third time in the match, but Hibino would not be denied a straight sets victory to claim her second WTA title, adding to her victory at the Tashkent Open in 2015.
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