The store was wonderful and I spent more than an hour there filling my shopping basket with an assortment of cards, sticky notes, mini notepads. All of it is almost too good to use.
This is a photo of the much smaller store in Marunouchi (just near the Peninsula Hotel which is an easy landmark to spot).
If you find yourself in Ginza though, just look for the giant red paperclip. It's hard to miss and worth seeking out.