Need tips for the best beaches which are not crowded

Hi there, i am planning to stay in okinawa for 4 days in april please suggest me some good beaches with peace and no crowds. Do i need to visit kerama islands for the best beaches or can i find it on mainland

Also please suggest me where should i stay? Naha or onna?. I cant rent a car so please suggest accordingly. My main priority is to see pristine beaches, best seaside cafes and calm vibes. Thank you