Imagine you feel wronged by your employer and find simply sharing your work woes with friends and chat groups inadequate. You want compensation and acknowledgment that your employer acted unjustly.
Suing is not your only option. Prefectural labor boards may hear your case and bring your employer in for reconciliation.
A few years ago I was given a pay cut at my last university for political reasons. I had asked the university president, in a one-page private letter, to consider replacing the Hinomaru Japanese flag flying in front of the university with an Earth flag, partly because the university was always squawking about how international they are, and partly because faculty were invited to share any ideas and concerns with our "open-minded" president. So when he told me the reasons for a 10-percent pay cut included my opposition to the Iraq war, and the "flag letter," and ended my evaluation meeting wagging his finger saying, "You should love the Japanese flag," I was shocked, but didn't know where to turn. Suing seemed a long shot.