Hanko misuse

Hello, I have heard that sometimes people steal other person's hanko to sign documents without their permission, for example, a divorce application.
Would this divorce be effective if the spouse finds out that his hanko was misused?
Can the person who misused the hanko get punished? (assuming that the hanko owner can prove the forgery).

Obviously these things can happen just as forging a signature can happen. But sometimes there are safeguards put in place to help prevent fraud (such as requiring witnesses who must also hanko the document). But it makes me wonder why you would ask these specific questions and it appears that you're planning to attempt to divorce your spouse without their knowledge, which I'm pretty sure would be illegal. Perhaps it would be better to consult a lawyer on what your legal option for your domestic situation. Free legal services for foreigners are often available at your local city hall. Or here is the site for the Tokyo Bar Association that offers free and cheap legal advice:

http://www.toben.or.jp/english/english_legal.html

Thanks, I will use those services for foreigners.