Tokyo has more Michelin-starred restaurants than any other city in the world — more than Paris and New York combined — but the most revelatory eating often happens at the other end of the price scale: a bowl of ramen at midnight, a sushi counter with eight seats, a yakitori joint under the railway tracks at Yurakucho. The city is serious about all of it.
The key disciplines to seek out: ramen (the regional varieties are dramatically different; Tokyo style is shoyu-based, Sapporo style is miso, Hakata is tonkotsu — try at least one of each); sushi (the Tsukiji outer market area and Ginza have excellent lunch-price counters); izakaya (Japanese pub-restaurants with sake, beer, and small plates — the best evenings in Tokyo happen here); yakitori (grilled chicken on skewers, eaten under the train tracks around Yurakucho and Shimbashi); and tempura (best at the counter, watching the chef work).
Breakfast at a standing soba shop near any major train station, costing under ¥500, is one of Tokyo's great pleasures.