Mikayo Taguchi loves splurging on her grandkids and children, whether for clothes or sporting goods or family outings. In Japan, that generosity matters — boosting demand by tens of billions of dollars each year.

"Those who are grandmothers and grandfathers often say that you can't look after your grandchildren unless you have money," said Taguchi, 60, a resident of Miyazaki Prefecture.

The savings-rich elderly spend about ¥9.7 trillion ($87 billion) a year on their offspring, including adult children who have struggled with lower wages during two decades of sputtering economic growth, according to Hiromichi Shirakawa, chief Japan economist at Credit Suisse Group. He estimated such spending last year accounted for about a third of the modest growth in total consumption.