This one is probably the hardest to tackle as there really isn’t a way around this one (The best cost-to-comfort option would be a hostel, and BOOK IN ADVANCE!) But if you decided that you were just going to roll the dice and figure it out later, there is a saving grace.
You can stay in Tokyo for about $40 a night. 24 Hour Internet and Manga Cafes will let you stay overnight. They have a shower and there is a sleepable lounge chair. A night here will cost you $30-40 and you can get there at any time. They are dirty and smoke filled, but you can’t expect much more. And if one is full, you can always find another.
I recommend Takarajima 24, an internet cafe / that also functions as a love hotel. That offers private rooms. You can read more here: takarajima24.com
The other alternative for low — cost to comfort is a love hotel. In Japan, love hotels are very clean. However, love hotels typically have a very high quality standard of living with more space, and the check-in is an automated vending machine process. A nightly stay is about $40.
Fast food is doable here, a quick bowl of ramen or a burger will end up costing you about $8usd-10usd on average with a drink included.
Traditional sit downs are a bit more expensive. So in order to maximize your economy, I suggest buying marked down food from the grocery store. If you wait until 9:30pm and visit a grocery store, you will be able to purchase a bento for the next day usually at half off, as well as discount sushi. You can purchase these for about $2usd after mark down, as well as purchasing a discount sushi set for about $2USD. There are several grocery store chains that discount after 9:30pm; however, I recommend this chain if you can find one.
If the weather is nice, it is actually cheaper to buy a bicycle than it is to take cabs for the duration of a 5-day trip. If you are interested in buying a bicycle, go to Don Ki Hote (see Shopping below).
However, if self-powered transport isn’t your idea of a good time, or you are not just traveling to outer areas of Tokyo or other parts of Japan. You should buy a JR Rail Pass before coming. You pay online for a voucher that you exchange at the Tokyo station’s traveler services office. They have English-speaking staff there. JR is the Japan Rail company and they operate many train lines in Tokyo. The pass cost about $243 for seven days, but if you are doing a large amount of rail travel with day trips outside Tokyo, it pays for itself. It is an unlimited travel pass for however many days you request. The pass is only available to foreign passport holders. You can learn more here: japanrailpass.net/en/
If you’re only traveling locally, a good idea would be to buy a daily fun-pass that allows you unlimited travel on all of the major subway lines in tokyo. Tokyo has several subway companies and travel is restricted based on which line you are buying a pass for, there are multi-line passes available so find out which lines you will be primarily traveling on before you come.
Don-Ki-Hote is the king of discount shopping in Japan and has several 24 hour locations in Tokyo. “Donki” is a must visit on your trip to Japan. You can buy anything from green-tea KitKats to a toilet seat that will warm your butt and play music while washing you. Any bill over 5,000 yen (about $42) will be tax free with a passport. Here is a list of Tokyo Donki locations. Seriously don’t miss this.
For the more dirty side, there is also a large discount mall called Takeya in Akihabara. You can find more information on it here: takeya.co.jp/english/ 