One fun adventure in Japan is to visit a Matsuri – local festivals usually around a shrine. Chances are that wherever you are staying, perhaps a couple of stations away, a Matsuri is happening. They usually run for a night to couple of nights. There is lot of local food and some fun games. The best way to find a local Matsuri in Tokyo is to look up the web http://www.gotokyo.org/eventlist/en/list
You can walk past the stalls and just point at the food you want to eat. Snacks usually cost 100 JPY for a stick of grilled meat to 500 JPY for a pack of Yaki Soba. Drink cost around 100 JPY for soft drink to 200 JPY for beer.