I understand japan isn't as exciting as it used to be, but they still have a pretty dynamic and influential popular culture. I understand their working population is declining relative to retirees, but eventually those old people will start to die. Anyway, its not as if this will be some sort of old people zombie apocalypse.

Random idea:

What if the votes of each age group were weighted to account for the size of that group, e.g. making the votes of 18-20 have the same weight as the votes of 40-42, even if there may be more people in the 40-42 group.

This would prevent an aging population from giving too many benefits to older age groups, and would encourage policies that consider long term impacts more.

> What if the votes of each age group were weighted

Because the principle of "one person, one vote" is widely (and correctly IMO) accepted.

In many places and for certain purposes (the US and the EU for instance), geographical regions have one vote, regardless of their population size.

It’s unclear that an age-based distribution instead of geographic distribution would be worse. But it would probably be unrealistic to achieve without basically completely upending existing political structures.

The EU isn't one country

The US is one country and disparate voting power between states(mainly in the Senate, to a lesser extent with the electoral college) is a real problem. I see little reason to make it worse. Although it's useful to rhetoric out how little sense the current system makes

The point of having both proportional and state-based voting is to incentivize both small and large states to stay in the union. The optimization is for political unity over perfectly representative democracy. It makes perfect sense when you consider the ideals and goals of its implementation -- that being a compromise in order to convince both small states and large states to cede large parts of their sovereignty to what at the time were effectively foreign nations.

This made sense back when the states were actually mostly self-governing polities, and there were relatively few pertinent issues on the federal level. But this is no longer the case today, and in practice, EC and Senate result in a "tyranny of the minority", where the minority can not only veto the majority's agenda, but actually push their own instead.

The small states who have excess control in the Senate cannot tyrannize the large states (except by maintaining the status quo), because the House of Representatives still exists. No new policy can get passed unless both a majority of states' representatives and a majority of the population's representatives agree -- if they disagree, the worst you get is gridlock, not "tyranny of the minority".

And this system wildly over-represents the landowning elites as a result

One person, one vote is proportional representation, which is not widely practiced.

What is actually practiced is 'One collection of zip codes, one vote.'

You don't need to weight the groups, since everyone experiences all ages (not counting early death).

My proposal is: Multiply the number of house reps and senators by ten (for instance). Each representative now represents a district / state as well as a decade of life (for instance). When voting for an age-graded role, your vote only counts towards the decade of life that you're currently in. You can only run for a position that matches your age range.

This would have a number of advantages: Disrupt two-party dynamics. Increase granularity of representation. It's harder for older folks to take younger folks hostage. Younger folks will feel more enthusiastic about voting for someone who actually represents them.

Probably, you'd want to fiddle with the numbers based on age demographics. 7-year intervals is probably the right number, with a big bucket for people over a certain age. (So, 18, 25, 32, 39, 46, 53, 60, 67, 74+) might be right.

>Disrupt two-party dynamics

and that's why it'll never happen without a revolution

Shades of 3/5ths Compromise maybe? https://en.m.wikipedia.org/wiki/Three-fifths_Compromise