Don Quijote (known in Japan as just "Donki") is a chain of stores in Japan which sell pretty much anything and everything - the following photos of their Akihabara store shows you exactly what I mean with hardly any wall space visible.
Whether you are after daily life products or otaku goods - Donki is certainly worth dropping in when in Akihabara - just walk along Chuo Dori street - you can't miss it.
The same building is also home to the At Home Maid Cafe.
〒101-0021 東京都千代田区外神田4丁目3-3