"At the time [after the earthquake] Facebook was the way we kept in touch privately. People couldn't use their phones, and it was the easiest," said Takahiro Chiba, an official who organizes volunteers in the eastern seaside town of Kessenuma, where tsunamis washed huge ships ashore and caused massive oil fires.
"Now it's more for public groups, for posting notices and information about our activities. Volunteers are still coming, and this is how we reach them."
Some new social networks were born out of the disaster. Line, a Japanese chat app that launched in June of 2011, is now common in the country and hit 100 million users in January of this year, with another 3 million signing on each week.
"People were looking for a way to communicate and had trouble doing so with mobile calls and email," said Jun Masuda, the executive in charge of the service's strategy and marketing.
The disasters that hit Japan's northeast coast in 2011 were a human tragedy. The earthquake and tsunamis left over 17,000 dead or missing, with 310,000 still in temporary housing, many unable to return home because of radiation concerns related to meltdowns at the Fukushima Daiichi nuclear power plant.
In the aftermath, services like Facebook and Twitter surged in users and have become part of Japanese society. Even so, some have started to wonder if there are other, better kinds of social networks.
"I have 800 friends on Facebook, but I think that less than half of them see what I'm saying," said Miyamoto, the volunteer nurse. "Lately I've realized I need to create more events where people get together in the real world."