Mariko Horiuchi, a 30-year-old part-time English-language teacher living in Tokyo, wonders if she should trust what the government promises for her future: a sound retirement covered by state pension benefits.

She does not take the promise at face value. Instead, she seriously worries whether she will receive benefits worth what she will have paid over decades of working.

"I've heard (that the) returns will be too small," Horiuchi said, noting many of her friends working at temp-staff companies have not paid premiums for the Basic Pension System, which is supposed to cover all workers aged between 20 and 60. "I'm wondering if I should pay the premium next month."