Photo: Mark Frauenfelder

Last month I went to Japan with my family. It was my 10th time in Japan. But until this visit, I had never gone to any island other than Honshu, the one that has Tokyo, Kyoto, and Osaka. This time we went to Kyushu, which is south of Honshu. The largest city is Fukuoka, with a population of 1.6 million. It's small compared to Tokyo (pop. 14 million), but it has a lot of the exciting things Tokyo has to offer, with great walking neighborhoods, temples, shrines, restaurants, and shops.

It has an excellent subway system, too. We loaded up our digital Suica cards and rode it multiple times a day. I added the Suica card to my Apple Watch, and all I had to do was put it near the subway turnstile sensor to pay for my ticket.

Here's a sign we spotted on a subway car that gave us a chuckle because it uses the word "rucksack" in quotes. In the US, rucksacks are usually thought of as large backpacks for outdoor adventuring.…