In spring I recommend doing hanami , but the cherry blossom season is finished now, so why not have a picnic and drink in a park with a bunch of friends?
Go to an electronics store and use the massage chairs. You can stay as long as you want. Sleep, unwind, recharge your batteries. You'll never pay for a massage again!
Teacher, 29 (Aussie)
Yoyogi Park on a Sunday is hard to beat, but if it rains, head down to Tower Records. There's a huge selection of music, most of which can be listened to in-store.
Public libraries are great if you are interested in reading or studying. Nowadays they are really clean, many have cafes, and they are open until 8 or 9 p.m.
Teacher, 37 (British)
If you have the time, go to a major road service area and try hitch-hiking. A friend and I made it to Hiroshima from Tokyo in 24 hours and met some fantastic people.
If you go to the basement of big department stores like Mitsukoshi or Takashimaya, you'll find many free samples of delicious food to try, and sometimes wine.