Short board rental windsurfing

Hi, I’m planning to go to Okinawa around September 18th and I would like to go slalom sailing if it’s windy. Just a few questions:
Could anyone recommend a beach to go sailing for a day or two? Need to rent everything- how much would that roughly set me back? And finally what are my chances of getting some wind mid-September? Thanks in advance!

by Sossie-sizzler