I got an emergency food set for my family of four about a year ago. It includes three days amount of rice, bread, other dishes such as curry, cooked meat and fish, vegetable soup, some sweets and of course, bottled water. I checked it online and ordered it. I liked it because it also had a heatpack, a tool to make the retort-packed food hot when no electricity or gas available.
Since Japan has many volcanoes, it is a natural disasters-prone country including earthquakes and tsunamis. As a result, we have the most advanced technologies to mitigate disasters. Food is no exception.
For example, my food pacage has a variety of cooked rice: plain one, chicken tomato pilaf, Japanese style soy sauce flavored pilaf, and Chinese style fried rice.
I hope no disaster will hit my district, but if it does, better safe than sorry. 備えあれば憂いなし in Japanese literally means 'Preparing well will save the trouble'. I also bought some other things: flashlights, blankets, and so on.
Tourists might want to bring at least some nutritious sweets like chocolate and nuts just in case.