Troops had found the man - aged in his 20s, apparently in shock and unable to speak - inside a wrecked house in the disaster area of Kesennuma city in Miyagi prefecture, the Self-Defence Forces (SDF) said earlier.

"When the person was transported to hospital, a fire department official recognised him as an evacuee who had been in a centre for a week and who had tried to return to his home," an SDF spokesman later told AFP.

The man had temporarily returned home, together with his family, and was alone on the second floor of his half-destroyed house when he was found by a pair of troops, Jiji Press said, citing SDF and hospital sources.

The man was identified as Katsuharu Moriya, Kyodo News agency reported.

A 9.0-magnitude earthquake on March 11 triggered a giant tsunami that flattened Japan's northeast coast and killed 7,197, according to the latest police death toll, with almost 11,000 officially listed as missing.