There is no English version (yet), so other than finding guides and help online, you'll be forced to research the Japanese yourself, which makes for good learning!
This cute little app might look familiar. That's because it was made by Hit-Point, the same lovely people who gave us Neko Atsume ねこあつめ, the cat collecting game for us crazy-cat-lady wannabes.
Tabi Kaeru 旅かえる, or "Travel Frog," is a similarly slow experience and less of a game than a way to distract yourself a few times a day.
In the app, you have a little frog who goes on journeys. You help it pack a bag of food, tools, and charms, and in return it sends you pictures and local specialty omiyage. All of these supplies and souvenirs have short descriptions and will affect where it travels next.
There is a surprising amount of text compared to Neko Atsume and you actually need to understand what you're reading to fill out your collections properly. This presents the opportunity to learn new words and a little about Japanese tourist locations.
Fans are even making maps of all the tourist spots your frog is visiting.
Learning about locations and their regional specialties on your phone, in Japanese, doesn't feel much like studying, but it can help you quite a bit. There are also some really great, practical ideas you can steal the next time you go to Japan for gifts to bring back for your friends and family.
If you need help understanding parts of the game, or you just want to make sure you're understanding the Japanese properly, a cool guy named Damian Vila made an English follow-along tutorial you can use. But I'd recommend trying on your own first—maybe keep a little notebook or add the new words you encounter to your learning method of choice.