Rei Kawakami was on a train to the airport after a conference in Seoul in October when she heard about the fire engulfing Shuri Castle in Okinawa.

"I've been to Shuri Castle and I knew that for the people of Okinawa, it was part of life," said the 39-year-old associate professor. After reading news reports that students were so shocked by the castle's destruction they were unable to go to school, Kawakami felt compelled to act.

"I have children and I imagined how overwhelming it would be if they were the ones who experienced this," the computer vision specialist and University of Tokyo graduate student said. "I could not bear to do nothing."