Thank you so much for the information.
I asked a Japanese guide and she emailed me this information. I’m Posting it that it might help others.
To get to the city view bus, passengers need to go to the down town area “Tenmonkan” first. It takes about 30 minutes from Marine port by car or bus.
Passengers usually take a shuttle bus from the port. Depending on the ship, it would be free or not.
In the downtown area, there is an information center on the first floor of a big building named Sen-treasure at the center of the downtown area. Cute pass is available there. And a bus stop for a city view bus is near there.
Hope this helps others.