[Sangetsu]

You can get a room at the Prince hotel in Shinagawa (metro Tokyo) for 8000 yen a night. Train and bus transport around the city will run you about 1000 yen per day. Train fare to outlying areas will cost more, generally about 800 yen each way. Food can be cheap or expensive, depending on your taste. A combo meal from McDonalds or Burger King will run about 700 yen. A prepared meal (boxed lunch or dinner) from a convenience store (they are pretty good) will be 300 to 600 yen. Vending machine beverages run 120 to 150 yen. Sushi from a garden-variety restaurant will be about 1500 yen. Chanko nabe (my favorite dish here) is about 3000 yen.

Souvenirs. The best place to get them in Tokyo would be Asakusa. There are hundreds of shops of every variety, selling pretty much everything. A pair of geta cost about 2000 yen, a yukata will run about 4000 yen. Fans average around 2500 yen. Besides the shops, you can visit the Sensoji Temple, which is Tokyo's most famous.

Amusement/theme parks/theaters. Admission to the Disney parks is about 5000 yen. Admission to water parks and such is about 4000 yen. A typical movie ticket is 1800 yen. Rides at places like Cosmo world in Yokohama are about 500 yen each.

Budget about 20,000 yen per day for your visit. Over the course of the week this should be enough for hotel, food, transport, a couple of attractions, and souvenirs. Bring comfortable shoes, as you'll be walking a lot. And bring a good camera, the more pictures you take, the better.