I doubt Hot Topic will be in Japan, they aren't even here in the UK. [Isn't it purely an American thing?]
I've seen Hot Topic clothes and personally I don't really like them - the designs look a bit corny and not very well made [not to mention the price on them] but I've never had an item of clothing from there so I wouldn't lnow.
I guess the UK version of Hot Topic would be
Attitude Clothing but I think that company is based in America. They ship here though, the must have warehouses here and stuff, they send me the catalogue when it comes out too. There used to be really cool stuff in it but now it's mostly crappy emo stuff ¬_¬