Cristian comments

Accepting a declining population is not possible. Japan's economy would simply colapse and everyone would stop receiving benefits like health care and pensions.

Policies to increase the birthrate are therefore not only necessary but very much critically important.

"Throwing money at the problem" is definitely not good enough but also is MUCH better than not doing anything.

As others have mentioned, improving working culture is also a critical step.

Regarding immigration japan is not a very appealing nation for most people vs moving to other developed countries.

However, it does have many ways to potentially change that.

The introduction of digital services must become widely implemented to increase efficiency and also make english and other languages available for most processes.

Immigration policies must change to create a realistic path to permanent residency and citizenship.

All in all many things have to change to make a significant change but none of them are impossible to achieve. As long as there is political willpower.