144 hour visa with cruise

Hello. Very nervous about the 144 hour visa. We fly into Shanghai from the US on a Sunday. We then depart from Shanghai 2 days later on Tuesday on a cruise that goes to Japan (no China ports.) The cruise ship returns to Shanghai a week later, and we get off the ship and go straight to the airport to board the plane back to the US. So it's US-Shanghai-Japan-Shanghai-US. But travel to Japan and back is by ship, not plane. Do we qualify for the 144 hour visa?

And do I understand correctly that to get the 144 hour visa all we need to do is look for the 144 hour visa desk when we go through immigration in Shanghai and show them our cruise documents?

Thank you for your help!!!