Negotiate with department stores, coffee shops, and other local public establishments which may allow you to show your photographs. If you are rich enough to rent a gallery, it's quite easy. Just contact the gallery and reserve a time slot. Be prepared to pay around 20,000 yen per day to rent the gallery. The minimum rental period is usually 7-10 days.
Some rental galleries require certain standards in the quality of the work to be exhibited.
If your work does not meet their standards, you might be rejected. Exhibition-quality prints may also be required. The total bill will be considerable. If you pass the judging, you will be notified of an exhibition slot which is usually about a week long and a year in advance. You are competing against many other people, so the chances of getting in are pretty slim.