I will be going from Tokyo to shanghai to Okinawa and will spend 4 days in shanghai.

Karen, as you will go from Japan to Shanghai and then back to Japan, I worry that you can't use the 144-hour free transit. If you have a Japanese passport, that will be ok because Japanese can enter China free for a 15-day stay. If not, you need to purchase a ticket from Shanghai to a third country or apply for an entry permit in advance.