Arriving in Shangai on Int'l flight, departing by cruise ship

If your itinerary is:

Seoul - Shanghai - Japan

And you don't have any additional stops of any kind within the mentioned three points, you are both definitely eligible for 144 hour visa free transit in Shanghai area, comprising of Shanghai City and the provinces of Jiansu and Zhejiang.

All you have to do is to print out your cruise tickets from Shanghai and also your accommodation booking for your first overnight in Shanghai. You will take those printouts with you.

Also, you will declare at check-in in Seoul that you will travel to Japan via Shanghai using 144 hour visa free transit. After a short inspection of your, primarily cruise ticket, you will be allowed to board the plane.

Upon arrival in Shanghai, you will approach 144 hour visa free transit counter where you will fill out a blue form. You will present your ticket and passports to the immigration officials and shortly after, you will receive a sticker in your passport and you will be allowed to exit the airport.

When you find yourself in China, you are allowed to travel and stay within the area I have mentioned as you wish. Of course, until departure of your cruise, that you want to catch.

Basically, that's it.