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My recommend food is Unagi!
You can encounter almost everything in Tokyo. All the great food gather in Tokyo, but there are some local food of Tokyo:
Monjayaki is the most famous local food of Tokyo. It's known as a different version of Okonomiyaki, but has different ingredients. It looks kind of disgusting to some, but tastes really good!
Fukagawa-Meshi is a type of rice. Rice is cooked with clams, which means the soup of clam soaks into rice, making a great taste.
Dojo, is loach. Loach hot pot, can you believe? It's cooked with a broth mainly consists of soy sauce. I have been to Komagata Dozeu, a long established restaurant serving Dojo-nabe. The place had a great atmosphere!
You can find more local food of Tokyo from here: https://hubjapan.io/articles/top-10-tokyo-local-food-you-must-try
There are also hundreds of great ramen shops and Izakayas. You should definitely try one of them. Spending some time in authentic Izakaya must be a memorable experience!