COL in Japan in general is about as unhealthy as it is in California.

people are working themselves to death just to scrape by.

if governments want population growth, they have to siphon wealth away from their corporate overlords and nurture the working class.

I doubt the fertility rate is much better in the scenic, middle-of-nowhere areas. People just don't want kids, and now there's the option to have sex without them.

Tokyo isn't having population decline, its the countryside.

They need to grow it a lot more, it's not even close to The Mark of Gideon levels yet (aside from some trains during peak hours), so they have a lot of work to do! Correction, Worf doesn't consider that work.

There are plenty of people living in Tokyo because it has the highest wages, best educational institutions, and most job opportunities but not because they want to. However, I'd honestly say that's more of a minority.

Greater Tokyo also include places that look like (of course slightly more compact) US suburbs. Sure, the further toward central Tokyo itself you go (particularly inside the Yamanote line), the density increases a lot, but it's also not some hellscape. I moved to the countryside to farm, but I otherwise mostly enjoyed my life in Tokyo. I could have found farmland closer to Tokyo itself, but I wanted to get north before it gets any hotter, so not a problem of Tokyo itself.

Don't get me wrong; I wish there were investment to split things up some more and get the people who want to be out of Tokyo out of it. This would require having those job opportunities and educational institutions split up as well. This isn't going to happen.

The hardest part about raising a family in Tokyo, from those I know who are doing it, is childcare. There are free and subsidized options, but they're hard to qualify for and having waiting lists and lottery systems. That part sucks. It's not impossible for most families, but it does sometimes end with one parent not working for a time. Better childcare leave policies have helped here, but not enough (and some shit companies still try to pressure women to quit instead, but that's another issue).

Up here, we have more availability and my village actively pays people to move here (I was one of them, but those with families get even more benefits) and offers free or heavily-subsidized childcare. Still, while the incentives are nice, they're not bringing those mountains of job opportunities or educational institutions with them on their own.