In Japan, you can also submit your divorce papers by postal mail to the municipal office (city hall).
You can download the divorce form (Rikon-Todoke) from some municipal offices via the Internet. Generally, the form can be used at any Japanese municipal office.
Sapporo city http://www3.city.sapporo.jp/download/shinsei/index.html
However, if there are any mistakes, you will have to go to the municipal office to make corrections, so it is strongly advised to call the municipal office (Koseki-gakari) well in advance and make sure that your divorce form is filled out correctly.
Also, if you are a foreigner, be sure to check whether your home government will allow you to get a divorce by just mutual consent, without going to court.