It has knocked them off the top of the global longevity chart for the first time in 26 years, according to government data.
Japan's health and labour ministry said the average life span of Japanese women fell by 0.4 years to 85.9 years last year, putting it behind that of women in Hong Kong, who live for an average of 86.7 years.
The large number of elderly victims was a defining characteristic of the disaster, which killed almost 16 000 people. Statistics show that more than 56% of those who died were aged 65 or older and almost three-quarters of those missing were older than 60.
More than 90% of the victims drowned or died from injuries sustained in the tsunami, compared with a tiny number who perished in the magnitude-nine earthquake that preceded it.
In small towns and fishing communities with ageing populations, many victims were unable to flee quickly enough before being swept away by the waves. Others were stranded at home and could not be reached in time by younger neighbours.
The high number of suicides also played a role in the drop in women's longevity, the ministry said. Suicide rates have fallen slightly among men in recent years, but have risen among women. The number of suicides in Japan exceeded 30000 last year for the 14th consecutive year.
The average life expectancy among Japanese men fell slightly to 79.44 years, leaving them level with Italians in the global rankings. Swiss men head the chart with an average life expectancy of 80.2 years.
Experts attribute Japan's impressive longevity statistics to a diet low in fat – although high in salt – and to strong relationships with neighbours, universal access to healthcare and a comfortable standard of living after retirement.
Despite the slight drop in life expectancy, the ministry figures show that a large proportion of Japanese will live well into old age: more than 45% of women and 20% of men are expected to celebrate their 90th birthday. – © Guardian News & Media 2012
Have something to say? Tweet or Facebook us on @Bhekisisa_MG
Japan, one year after the tsunami: 'We can't just stay sad'
Japan plans new tsunami wall at nuclear plant
Work at a non-profit media house? Then you know your job is not just reporting anymore.
As deaths mount, take an inside look at the detectives working around the clock to solve the country’s medical mystery.
Until now, the national and provincial health departments have not been able to say where services are provided. Here's how we found them.
Bhekisisa means "to scrutinise" in Zulu
In South Africa, Zulu patients who would like to be thoroughly assessed by a doctor, would ask the physician to "bhekisisa" them.