Norio Kimura, 50, who lost his father, wife and daughter in the March 11, 2011 tsunami, searches for his missing younger daughter Yuna near his home inside the exclusion zone in Okuma, near Tokyo Electric Power Co's (TEPCO) tsunami-crippled Fukushima Daiichi nuclear power plant, Fukushima Prefecture, Japan, Feb 14, 2016. [Photo/Agencies]

Such tenacity can be partly explained by views of life and death widely held in Asia, experts say.

"Once dead, a body itself is often seen and treated as an object in the West," said Shinichi Niwa, adjunct professor of psychiatry at Fukushima Medical University's Aizu Medical Center.

"In Asia, there is a strong belief that one's spirit stays with the body and they are not separated," he said.