Do I need a visa fnr the Millinium sailing from Shanghi 9/29 leaving Shanghi for Tokyo 10/9?

The ship will be in port 9/29 -10/5, (leave Shanghi and back 10/9) and will leave Shanghi 10/9 for Tokyo.
Do we need an entry permit to board the ship? Do we need an entry permit to visit the city while it is in port (less than 24 hrs).
The ships schedule is 9/29 - 10/5 Shanghi to Shanghi - 10/05 10/09 Shanghi/Shanghi and 10/9 to 10/16 for Tokyo'
Do we need an entry permit from Shanghi/China for this trip? Tokyo/Japan to leave for USA>
We have USA passports.
Your prompt response is appreciated.
Thank you..