If you are a first year JET currently using an International Drivers Permit (IDP) but planning on driving next year, we recommend starting the process of getting your Japanese Drivers License now (if you haven't already!).
During July, driving centers get very crowded and it often takes up to six weeks until the next available appointment. People will also find that they may have to take the driving test 1-2 times before they pass, so you don't want to be stuck with an expired IDP and have to take a taxi to work (it has happened to JETs before).
You can find detailed information about the process at this page of the website (Shout out to Sarah D. for compiling such a complete guide to the process!).