No.1 seed Osaka — a two-time runner-up in this event before it moved from Tokyo to Osaka — overcame Yulia Putintseva and Elise Mertens in straight sets after rain prevented her from taking to the court on Friday, winning eight of the last nine games against the latter to triumph 6-4 6-1.
The win over Putintseva was a particularly sweet one for Osaka, given the Ukrainian had won their past three meetings in straight sets, including a first-round success at Wimbledon earlier this year.
While Osaka's presence in the final is no huge surprise, even if she has not made a decider since winning the Australian Open in January, Pavlyuchenkova has exceeded all expectations this week.
After thumping Misaki Doi 6-2 6-2 to end hopes of an all-Japanese final, Pavlyuchenkova shocked No.4 seed Angelique Kerber with a 6-3 6-3 win.
The Russian will now contest her first final of 2019, having not dropped a set so far in this event.