Take care of your health. You can get normal medicine at drug store. Aspirin, digestive, soar throat, etc, If you have daily medicine, you should bring it with you. I'm not trying to scare you. Just want you know some hints in Emergency.
Japan is very famous of earthquakes country.
Actually Tokyo area and Tokai area are told that there will be a big earthquake. Following are the minimum things you should be aware of if you have encountered a big earthquake during your stay. Don't be panic. Be calm when you have it. Extinguish any fire around you.