How the four days split
The failure is one list that holds Kokusai-dori, Shuri, Mabuni, American Village, Manzamo and the aquarium. Four days fit four axes. Miyako and Ishigaki are another flight — not this station.
Where you sleep decides one less rebound
Naha and Shuri only: sleep in Naha. A coast day: Onna or Chatan. An aquarium day: Motobu or Nago. Do not return to Kokusai-dori every night.
Arrival day is not the north
The landing day is only Naha or Shuri. The aquarium and Cape Hedo sit at the north end — put them on a middle day with a car, not against a flight. The monorail ends at Tedako-Uranishi; Shuri is mid-line. The Shuri exit is steps, so do not stay up at the castle after the last train.