An 80-year-old woman and her teenage grandson were plucked from the wreckage of their home today, nine days after an earthquake and tsunami devastated north-east Japan.

Rescuers patrolling the city of Ishinomaki heard the plaintive cries "Please help! Please help!" from 16-year-old Jin Abe, shivering on the roof of his collapsed wooden home.

Draped in layers of towels, he had only been able to crawl out of the wreckage today. Still trapped inside was his grandmother, Sumi Abe.

The two had been stuck there since the March 11 magnitude-9.0 quake struck off the coast of Japan.

Police called in personnel with better equipment to help rescue the woman, whom police found wrapped in several blankets, on top of a collapsed closet.

The elderly woman's weak legs kept her from walking, said police spokesman Shizuo Kawamura.

Grandmother and grandson were weak but conscious, having survived on the food they had in their refrigerator, said Mr Kawamura.

National broadcaster NHK aired dramatic video of the rescue, which showed a stunned, though coherent, woman. She gave her name when asked.

"Are you hurt?" a rescuer said.

"No," she replied, and asked about her grandson.

Both she and Jin were taken to a nearby hospital.

It emerged that an aunt had asked police to search for the missing pair. Today, Jin's father, Akira Abe, said he had never given up hope of finding them alive.

"I always believed they were alive," he said at the hospital.

The rescue offered Japan an uplifting piece of news amid colossal devastation and sadness with thousands of dead and missing. Still, Mr Kawamura said he wasn't smiling.

"We have too many other victims to find to take the time to celebrate," he said.