[Sangetsu]

A standard work visa is for 1 or 3 years. In order to get one you need much more than a simple travel itinerary. First you need to have a sponsorship form filled out by your employer, and a copy of your labor contract (which are generally good for one year). As a foreigner, in order to qualify for the job, you will need an original copy of your 4 year (or better) college degree.

It sounds like you are entering Japan with a working holiday visa, which, as you stated, is only good for 6 months. There are no educational or employment requirements necessary to get a working holiday visa. On the other hand, you will not be able to extend the visa in Japan, you will have to return to your home country and reapply.