Great news: When large-scale natural disaster happens in Japan, within 72 hours, unified SSID “00000JAPAN” will be launched, and regardless of which carrier you are using, and regardless of where you are in Japan, you can use this Wireless Internet for free.
Japan learned from the natural disaster back in March 2011. During natural disaster, many of the telephone and mobile phone carriers becomes unusable. It is impossible to predict which carrier will be down, and where. Also, in many of the cases the Internet was a useful network to communicate, with examples such as people getting their lives saved by communicating via Twitter. In September 2013, experiments were conducted in Kamaishi and Sendai, in order to publish a guideline on opening public wireless LAN during natural disasters.
Disclaimer: The opinions expressed here are my own, and do not reflect those of my employer. –Fumi Yamazaki