Once you move in, there will be lots of red tape to cut your way through:

When you move in, it is common courtesy to greet your landlord. Especially in Japan, first impressions are very important.
　

When moving into a new apartment, introduce yourself to your next door neighbors on both sides, and also those above and below you. When moving into a new house, you should introduce yourselves to your neighbors in the three nearest houses to your right, and the three nearest houses to your left. Traditionally, this area (three houses in any direction) was called the Muko Sangen Ryodonar. It was an organized group of neighbors who help each other in various ways.　

It's best to introduce yourself to your neighbors on the day you move in. It's nice to bring a small offering or gift, such as postcards, or some sort of candy or sweets. The standard amount spent on this sort of token gift is \500～\1,000. Although gift giving in this situation is a Japanese tradition, if you fail to do it, your neighbors will probably understand considering you are a foreigner.

In case of emergency, it is your neighbors that help you most. Having a good relationship with your neighbors is important. If they like you, they are more likely to tolerate whatever you may do.

It's a good idea to send postcards to friends and relatives letting them know that you have moved, and telling them your new address and phone number. Try to do this sooner than one month after you move.