For those of you versed in the intense world of kettlebell training, moving to Japan may prove slightly taxing if you want to continue your training at a high level. More details follow:
High quality kettlebells ARE available, but you're going to pay top dollar for them. If that's what you want, then this Japanese guy sell imported Dragondoor bells. Prices are not totally unreasonable, but expect to pay around 35,000yen for a pair of 24kg bells.
Other than that, you can contact IKFF Japan's Mark Atkinson. Mark has been at the forefront of Asian KB training for a while now, and is a friendly, helpful guy. He sometimes has pro-series bells made to sell to those interested, and at a lower price than his Japanese competition above. I just bought two 28kg bells from him for 30,000yen. Mark's "gaijinkettlebell" blog resides here. The legendary Steve Cotter also posted a short video interview with Mark on Facebook.
There is a small Crossfit presence in Japan. I know of one in Tokyo (Chakara Crossfit). I contacted them just recently and discovered that they now have a wide selection of KBs which they use regularly. Well worth checking out if you're in the area.
Buying Cheaper Kettlebells in Japan
A good solution to no kettlebells is, surprisingly, Amazon.co.jp. Searching for ケトルベル there will throw up several pages of products, including some frankly hilarious-looking DVDs. I bought 2 of the silver (ALEX) 20kg bells, and one of the 32kg ones. I can honest say that the quality is pretty bad. The handles are rough like dumbells, and even thinner. With a tough file I was able to make them usable.
A much better budget solution is the sports store Xebio, who you can shop with online here. Xebio stock a limited range of weighted KBs. They aren't superb quality, but the handles are a good size and the overall feeling is fantastic for the price. Maximum weight is 25kg, of which I bought two for under 10,000yen, although the price seems to have gone up a bit now (about 13,000).