I live in a country with much better worker’s rights then Japan or the US. I’ve gone through disputes with employers. I can tell you that it’s rarely worth the battle. And if you do “win” you wouldn’t want to work at that place any longer. If it’s about something that could pay out big, it’s usually better for your mental health to have left that place a long time ago.

Being realistic is knowing when it’s better to move on and find a better job. Sticking around just so you can “win” a legal battle will just make your life miserable.