"Older people tend to spend proportionally more of their income on food and energy so a rise in inflation tends to affect this group more strongly," said Sarah Boumphrey, head of countries and consumers research at Euromonitor.
(Read more: World's Oldest Person Dies at 116 in Japan)
Japan, one of the world's fastest ageing nations, is home to a booming population of senior citizens. A staggering one in four – or 31.86 million people – are aged 65 or older – significantly higher than neighbors South Korea and China whose elderly populations currently stand at 12.2 and 11.1 percent of their overall populations.
On top of rising inflation, the looming consumption tax on goods and services – which is due to rise from 5 percent to 8 percent next April and to 10 percent in 2015 – could also prove burdensome for pensioners.
"That's going to be a negative for [the retired elderly]. If your income doesn't change, the sales tax will be burden," said Tomo Kinoshita, chief economist, Japan at Nomura. 61-year-old Noriko Ishihara, a retired nurse based in Tokyo, told CNBC she would need to cut back on spending if the tax is implemented.
"Expenses will increase if tax goes up. Since my income will not increase, I think I will hold off some buying. I need to think about how I should cut down my necessary expenses," said Ishihara.
(Read more: Can Japan's Elderly Become Its Growth Engine?)
"I thought Abenomics would be something that could bring benefits to the nation. I was expecting that, but cannot feel it," she added. One bright spot, however, is that of Japan's nearly 32 million senior citizens, 27.9 percent of the men and 13.2 percent of the women are still part of the labor force.
"In the longer run at least, wage growth should pick up in line with higher inflation, so this source of income should be reasonably well protected," said Thieliant of Capital Economics.
A reason for their high rate of participation in the workforce is because the country has the longest life expectancy globally – alongside Switzerland and San Marino – with men and women living to an average age of 83, according to the World Health Organization. In fact, women in the East Asian nation have the longest life expectancy worldwide at 86, compared with 79 for men.