From the department stores of Ginza to the souvenir shops of Naha, there's no doubt that Japan is a great place to shop, with something somewhere for every taste and budget. More than that, though, there are some stores that are tourist attractions in their own right, being unique to Japan in one way or another. Here are a few ideas for your itinerary:
1. Electronics Emporia
There are a handful of chains - Bic Camera, Yodobashi Camera and Yamada Denki are among the most prominent - whose stores are overflowing Aladdin's Caves of all things electronic, from the grandest home theater system to memory cards and light bulbs. Even the medium-sized town where I live has an eight-floor store! Plug your iPod into twenty pairs of headphones, watch a huge 3D TV, try out a massage chair, and marvel at the jaw-dropping variety of everything.
2. Hundred-yen stores
For household goods, snacks, stationery and much more, a good bet is the ¥100 (plus tax) store, which you'll find in any town of any size. The quality and value is higher than in dollar stores and pound shops overseas, and again, the range of goods is impressive, with more types of chopsticks than any one family could need, for one example. They're also great places to pick up gifts and souvenirs, and of course there's no need to tell your aunts or nephews exactly where you went shopping.
3. Don Quixote
Anything you can't get at a ¥100 store is likely to be found at your local Don Quixote, a chain of discount stores usually found near larger and busier stations, popularly known as Donki (the stores, not the stations). Clothes and cosplay outfits (lite versions), food and liquor, novelties and character goods, all burst from the shelves of the cramped aisles; it's fun to just wander round and see what surprises you find around the next corner.
4. Tokyu Hands
Like a more upmarket version of Donki, Tokyu Hands also boasts a bewilderingly eclectic range of goods, if anything even more diverse, but of markedly higher quality, usually stylish and often quirky. Woodworking tools, imported beer, sushi clocks, horse's head or Buddha face party masks, "The Scream" ice trays, and more pens than you'll ever see anywhere ever, are just the tip of the iceberg. It'll take an iron will to come out empty-handed.
I've pinned this article to Shibuya because you'll find all of these within walking distance of the station, but you'll find them all over the country. Enjoy!