I guess Japan lags somewhat behind the Western world concerning natural sciences (except robotics maybe). This is not because Japan is inferior, mind you. The problem is simple: Most scientific literature is produced in English. European countries also produce a neat amount of science and are easily translated into English. It takes some time to translate it into Japanese, as most Japanese are not proficient enough to read it in English. If this translation happens at all, that is.
So I'd say, you shouldn't study there unless you are very fluent (even on a technical level) in Japanese.
Please take my statement with a grain of salt, I may be wrong.