Internet cafes are one of my favorite things about Japan. The photos for this post are from Fujiyama Internet Cafe in Kyoto, but many internet cafes share the same good qualities. Most internet cafes are open 24 hours so sleeping here is no problem. Some even have beds/futons/sofas you can sleep on. At an internet cafe, besides surfing the net, you have access to the following free things: drinks (usually everything from coffee and tea to sodas and even slushies), magazines, books, comics, tv, dvds, video games (usually PS2s but I can see in the near future some PS3s showing up), and some places you can even use some really fancy massage chairs, or even take a shower. There is food available but you usually have to pay for it, but some places to have some free food. Also some places have a partnership with a restaurant (usually a fast food place in the same building) that will bring you food. As you can see, Japanese internet cafes are a little different from what you might be used to if you come from the states.
There are different rates depending on what kind of room you get and the interenet cafe and at some places you have to fill out a membership application which might come with a small fee, but it is still much cheaper than going to a regular hotel to stay here the night… If you are staying for the night, just be sure to get the multi-hour pack if they are offering one. You can stay the night at internet cafes from about 1200-2000 yen. While obviously it would not be convenient to stay here long term, it certaininly would not be too inconvenient to stay here a night or two out of your vacation.
