Capsel toys are available all over Japan. But you will miss them easily if you are not interested in small toys or anime caractors.
Kids are somehow quick to find capsel toy machine and ask parents to buy them one. When that happens, I always talk back to my daughters "Sorry, no coin at hand."
Capsel toys are full of excitement because we never know what item will come out. It also has a challenging aspect to complete the collection of the line. For example, "shop line" gives you a tailor shop, a doughnut shop, a flower shop, a hair salon. . . all of which are tiny enough to be put in capsels.
Once you start your collection, you will have to spend a lot of money! I warn you that it might be addictive.
How to get a capsel? Insert coins and turn the dial clockwise. Some are 100yen only, and elaborated miniature toys such as Japan's mini castles cost 300yen, even 500yen! Wow, I really have my kids away from this geek collection culture.