Here are some of the most visible signs in daily life that the time bomb is ticking.
There are now 68,000 people over 100 years old.
To put Japan's widespread aging in perspective, 2017 marked the 47th straight year that the country has broken its own record for the number of centenarians, or people living past their 100th birthday.
The trend still isn't widespread yet: One social worker estimates the total number of cases is in the low hundreds each year.
Prisons are turning into nursing homes.
About one-fifth of all crime committed in Japan is done by the elderly. Most of it is petty theft and shoplifting.
As crime rates among the elderly rise, prisons have effectively turned into nursing homes. Guards are made to bathe the inmates and help them get dressed, and experts say living conditions are too good to keep recidivism rates down.
Normally, younger relatives would take care of the inmates once they're released. But in some cases the costs (and loneliness) are simply too much to bear in a troubled economy, and seniors look to prison as the better alternative.
One of the main traits of the demographic time bomb is that young people focus a lot of their time on work instead of socializing, largely to keep up economically.
They still want to get married, however, so the compromise they're making is just partnering up with friends.
It's a real-life version of that game "If we're both not married by the time we're 40..." — except people are playing it in their late 20s.
Employees are succumbing to 'death from overwork.'
Long work hours are leading to a rise in cases of karoshi, or "death from overwork."
A report from October, which examined karoshi and its cause of death, found more than 20% of people in a survey of 10,000 said they worked at least 80 hours of overtime a month — a signal of just how desperate young people are for extra income.