Five years was not enough time for Prime Minister Junichiro Koizumi to overhaul the nation's ailing pension system.
Koizumi, who steps down in September, must be content with a 2004 stopgap reform aimed at preventing further deterioration of pension finances.
Now, whoever takes over the top post will have to address questions that have been put off if a long-term fix to the pension system's woes is to be found, experts say.