[samokan]

how? that depends on how long you are planning to stay or if you have a free place to stay.

things to be considered would be:

place to stay,
food, if you can survive with noodles only there are 100yen and less than noodles. Yoshinoya, and matsuya are also cheap way to eat.
train fare - cheap way would be to buy 1day tickets that can be used all throughout the day, usually starts from 500 yen - 3000yen, depending upon the coverage of the ticket.
souvenirs
entrance fees to place you might go ( most temples and museums have entrance free starting from 300-700yen )