I just ran across this newspaper article that was published late last year -
The text talks about learning how to program robots, and features a young group at a township community center. From the photo it appears that they are using the Lego Mindstorms Robot Invention System, and seem to be having a great deal of fun with it.
Frankly, I had the impression that Mindstorms, and Legos in general, weren't very popular here in Japan. I used to see regular Legos on the shelves at the local department store, but about a year ago they were displaced by an off-brand look a like. In the regular robot hangouts in Tokyo, like Tsukumo's Robot shop in Akihabara, you can find Mindstorms sets and individual components, but the prices are two to three times what you would pay in the US.
But, the more I look around, the more evidence I find that Legos are actually alive and well here in the Land of Wa. There have been regular feature articles in the RoboCon magazine focusing on Mindstorms projects. There are quite a few Japanese Mindstorms books available via Amazon Japan and other sites. And one of my favorite weekly television programs - Telebei Champions - devoted a full 90 minute broadcast to a Lego construction contest.