Japan experiences the most number of earthquakes in the world so the people are quite prepared. When I was living in Tokyo, my company gives all its employees an emergency kit to keep in their homes. After my assignment, I took mine home when I returned to Canada.
Inside, the contents are typical of what you will find in an emergency kit including first aid kit, battery, flashlight, canned goods, gloves, bottled water, etc.
I also added a few small bills and coins in the local currency. Do you have an emergency kit at home?