I'm thinking here of Isetan in Shinjuku and Tobu and Seibu department stores in Ikebukuro, although all the major dept stores at Shibuya and Tokyo stations should have similar food basements.
Always busy and noisy with the calls of the sales staff touting their wares, they give an insight into the astonishing variety and sophistication of Japanese cuisine. Also, they also frequently offer tantalising titbits to passers-by.
On an upper-floor, there is usually also a selection of reasonably-priced restaurants offering a variety of different styles of Japanese cuisine.
If you get off the JR Yamanote line at Shinjuku, you'll find Odakyu, leave by the East Exit, and turn right, Isetan is on your left about 200 metres.
Get off the JR Yamanote line at Ikebukuro and it will be hard not to find yourself in either Tobu or Seibu department store basement 1. Both have two whole basement floors of food.
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