If you are the person that miss your hometown during your trip to Japan, or you just want to try some other countries' food, you definitely can find most of them at Ueno. Ameyoko area is very busy during the day and night, you can eat international food, buy clothes, seafood, international ingredients and so on.
This time when I went there, I found one of my favourite hometown food --- Shanghai Fried Dumpling. I am not sure about the English name of it, it tastes just like "home". I ate this as a normal breakfast when I still live in Shanghai. Love it! Highly recommend!
I think everyone must a place called Ueno in Tokyo. Ueno is a funny place that contains very different areas. You will find Ueno Park packed of a variety of world-famous museums, then across the street, you will have an Ameyoko that full of local restaurants and random shops.
Also, there is a secret hidden Asia Market under the main building. You can find lamb, duck, port leg or those part of the meat that Japanese don't usually eat. I am so happy that I found one of my favourite Thai tea under there. You can also find lots of huge pack of seasonal powders, and cheap meat/seafood.