Searching through piles of bodies after Japan's March 11 tsunami, Kenji Sato was struck by the thought -- he could easily have been one of them, had it not been for his son born earlier that day.

In a fortunate twist of fate, Sato, a wiry descendant of fishermen in his coastal hometown of Minamisanriku, took time off from work to see his third child, Haruse, born at a hospital in a nearby port city.

Hours later, the only thing left of the nursing home where he would usually have been was a skeleton of steel pillars.

Nearly all 70 residents were swept away by the tsunami set off by the 9.0 magnitude offshore earthquake that devastated Minamisanriku, one of the worst-hit towns. Sato and his work mates set about the task of searching for them.

"I just confirmed that my wife and son were safe. Then, I spent days on end identifying bodies, looking for evacuation centers for the elderly," said Sato, 31, surrounded by his four-generation family at their home.

A year on, the Satos, who all survived since their house was built on a hill, are planning a quiet birthday with some cake and ice cream for the child who, his grandmother Kazuko insists, "was born to save us."

Because of Haruse's birth, Kazuko also took the day off from her job at the Minamisanriku town hospital. A boat still perches atop the 5-storey building, a chilling reminder of the height of the walls of water that ripped through the town.

Wave after wave razed the heart of Minamisanriku, killing around 1,300 of its 17,000 residents. Many survivors still live in more than 40 barrack-style temporary housing settlements dotted on the hills around what was once a lively fishing town.

"I saw my child for the second time only when we all reunited in early April," said Sato, caressing his oldest son in his lap. "I wish all that happened in between was just a bad dream."

Haruse was born around 4 a.m., a month prematurely, weighing 2.6 kg (5 lb, 11 ounces) and requiring intensive care due to low body temperature. But while the hospital in the nearby city of Ishinomaki was spared the brunt of the disaster, patients from across the region poured in, straining facilities.

"That's why I was told to leave him and had to check out three days after his birth," said Hiromi, 34, Sato's wife. Most Japanese women stay in hospital for a week after giving birth.

Weeks filled with anxiety ensued amid post-earthquake chaos, with checking on relatives amid aftershocks, scrambling for food and trying to get by without running water and electricity in the cold early spring weather.

"I was scared he wouldn't be able to leave the hospital, but when they said I can pick him up I was just very happy we could be together again," said Harumi, changing Haruse's Mickey Mouse nappies as he beat his arms and legs against the floor.

HAPPY CENTRE OF ATTENTION

After his birth, Haruse -- whose name means 'Bright Spring' -- was diagnosed with Down Syndrome, a genetic condition associated with some impairment of cognitive ability.

"I didn't know anything about it and was worried I won't be able to raise him properly, but we decided to bring him up just like our other two sons," said Hiromi. "The only difference is that we take him to a specialist doctor from time to time."

As she spoke, Haruse's older brothers, Anji and Oto, aged four and five, ran around the house screaming, fighting and stopping only for a bite of sakura mochi, a Japanese rice cake typically served in early spring.

"Sometimes I even think there are too many people trying to look after him," laughed Hiromi as Haruse's grandmother showered him with kisses and tickled him, making him squeal and laugh.

But raising three sons in a town resembling an eerie graveyard with only house foundations visible under a thick layer of snow will not be easy for even the most devoted family.

Minamisanriku's biggest employer, the fishing industry, is only starting to get back on its feet and rubble still litters the streets. Even before the disaster, young people had been migrating to larger cities anyway, to search for work.

Sato says that when not fighting with his brother, his older son is preparing to enter elementary school from April, while the four-year-old attends a nursery school in a pre-fabricated building near their house.

"When I drink with my friends, we laugh bitterly that our generation will spend the rest of our lives rebuilding the town," said Sato, now working at a different nursing home.

"It makes sense, because we want to do it for our children. Otherwise, they will have to abandon the place our family has lived in for generations.

"That just doesn't make sense."