I recently noticed that a lot of metal artists are spending most of their time in Japan. Is metal more popular over there or something. Basically, what is so great there?

Metal is no more popular in Japan than the US or anywhere else. If anything it's less popular here (in Japan) because pop music is so huge here. However, pop in Japan has much more 'rock' and 'metal' elements than the pop in the US, and I really like that.