Go to another account she hasn’t messed up on her phone, and make her watch as you use the password manager to get in. Then, you can tell her for sure that the tech is working, and you’ve done your part, but you cannot fix her behavior. If she wants to keep resetting her passwords all the time, that’s on her, otherwise, she’ll have to put a small amount of time and effort into adapting to using the password manager.

If she isn’t going to follow your suggestions and advice, why is she asking you for help? If she sincerely wants help, she needs to make an effort on her side to follow through.

This is a problem with psychology and boundaries, not a tech issue.

It’s hardly the sole cause of Japan’s problem, nor unique amongst developed nations. However, given the near total aversion Japan seems to have towards the notion of enabling immigration as a means to permanent residency for immigrants, it takes on a much greater dimension for the problem than it might in other nations that are more open to immigration. Barring a sudden and total reversal politically and socially on the question of immigration, Japan will have to do far more domestically to improve quality of life and work-life balance if they want to avoid a total demographic collapse.