Japan's Okuhara overcame the world and European champion 21-13 21-9 in a dominant display, and she will now meet sixth seed Tai in Sunday's showdown.
Okuhara quickly established a 10-4 lead in the first game and she never looked back from there, reeling off four consecutive points from 17-13 to move one game to the good.
The world number 48 was even more ruthless in the second, twice putting runs of five successive points together as she stormed to victory in just 40 minutes.
She will now face Tai, who faced a much stiffer test against Liu Xin.
Liu took the first game before Tai hit back to clinch the next two and close out a 17-21 21-16 21-16 triumph.
In the men's competition, 2012 champion Chen Long will have an opportunity to claim his second title in three years after overcoming Kidambi Srikanth 21-17 19-21 21-6 in his semi-final.
Srikanth won the China Open last week but there will be no repeat success for the Indian, who crumbled in the final game after fighting back in the second.
Chen will take on Son Wan-ho on Sunday, after the South Korean beat second seed Jan O Jorgensen 21-15 21-15.
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