How do pips and unlawful terminations work in Japan?

I worked at a tier 2 tech firm as a permanent employee earning 15mn plus.

Was given terms for an unfair pip or severance package and eventually took the severance. But want to understand here whether I should play things differently if there’s a next time.

Premise: was placed on a bs pip reason while on probation . Conditions of it was obvious a lot was made up and they just wanted me gone. I negotiated a 3 month package and took it. They told me they are forcing me into a pip regardless if I say yes or no. And will fire me with no benefits at the end.

Spoke to two lawyers and the labour bureue and got this feedback:

1: go through the pip and get fired. I have to be fired before anything can go through legal. Have to go to work. And after the 5 week pip get fired. I opted against this because I felt my hiring manager was already going to be super anal about document more biased datapoints against me

2: sue first. Send a lawyers letter and that will usually force the company legal team to take pause. Refuse to do the pip, but also state to refuse to resign explicitly. Lawyer told me that if I choose to sue, I can get usually 6-8 months since I’m on probation. But it will take a while and might be sticky if I also want to find a new job asap

3: negotiate. Which I did. Ended getting my clawbacks waived and getting three months severance.

by 69Tigbiddylover69