IF The japanese guy divorce the woman in japan...... Its suppose to have any document to prove ?? i was told by someone that she dun have any document to prove .

What you need is a document called Koseki Touhon, a family registry. You are not officially divorced in Japan unless your name is removed from Koseki Touhon (if you are female spouse).

The link below should explain it all.

http://www.crnjapan.com/references/en/koseki.html