Love this place. I haven't used the online store as of yet but when we visited Japan last year I dragged my girlfriend to no less than 4 different stores in 4 different cities.

Wicked place. It seemed to me that it was a department of geekery heaven and that they buy and sell second hand stuff as well as new items (There was a special section for people selling their collections to the store in the Kyoto branch).

It is an excellent resource for Macross Stuff (which is what I was after) as well as a healthy collection of Transformers (both Japanese and US)

Its also a heck of a lot of fun to just browse through as well. The first one I spent 2 hours on there.