JAL explorer pass question

I am taking my family of 4 to Japan in October. We have 5 days in Tokyo, 5 days in Osaka, and with the last remaining 5 days we wanted to go visit a friend I have in Okinawa. How does the JAL explorer pass work? Can I book a flight from Osaka to Okinawa, and then fly straight back to Tokyo from Okinawa? My friend says she uses peach airlines to fly to the mainland, but compared to JAL its pretty pricey.