One of the world's oldest twins, Kin Narita, has died of heart failure at the age of 107 at her home in the Japanese city of Nagoya.

Kin and her twin-sister, Gin, were hailed as national treasures by the Japanese Government.

On their 100th birthday, they released a "granny rap" record that topped the pop charts and opened up a lucrative late career for them both.

Kin, whose name means "Gold," lived 20 minutes away from her sister Gin, "Silver," in the central Japanese city of Nagoya, 190 miles west of Tokyo.

She is survived by five children, 11 grandchildren and five great-grandchildren.

Granny rappers

Kin had been in hospital last summer with a stomach ulcer, but was in exceptional form on her 107th birthday last August, when she and her sister appeared, wielding pink shovels, at a tree planting ceremony in the northern city of Sapporo.

The twins became national celebrities when their "granny rap" shot into the Japanese charts for their 100th birthday.

They frequently appeared on television talk shows seated side-by-side in kimonos, once saying they would save their media income "to provide for our old age".

It took them 100 years to file their first income tax returns because of the unexpected income from pop music, endorsements and guest appearances.

Ageing gracefully

They have been treasured as examples of graceful ageing in Japan, a society that reveres the elderly but is also deeply concerned about their growing numbers.

One-quarter of Japan's population will be 65 or older by 2015, according to government projections.

"We never thought we would live this long," Kin said on her 100th birthday.

"We could survive because we were twins. We need each other more than anyone else in the world."