Welcome to FT, gummy! It will be helpful if you re-ask this question once you have more specific information about where you are going to be located. In the meantime, the Japan forum has an excellent sticky giving general guidance. You might also start by looking at a guidebook.

Japan is a destination that hugely rewards doing homework in advance, so following this forum as well as doing other preparation will be repaid many times over once you get to Japan.

I am sure you'll enjoy your trip and again, welcome!