Topic: "Where are they Now?"

[PFG9000]

Um, no. That's not how it works. Conditions to a contract can be in place LONG after departure from your employer.

Exactly.  Contracts are however binding their language makes them.  If he signed a contract saying he wouldn't divulge certain info, then he can still be sued for breaching that contract even after he quits/retires.  At least, that's how it would work in the USA.  I don't know the first thing about Japanese civil law.