[Cyclamen]

You can't drive in Japan with a foregin license. You can drive in Japan for 1 year ONLY with an international driving permit (issued in your own country), but some countries' driving licenses can be converted into a japanese driving license absolutely without problems (and that's your case, since Spanish driving licenses can be converted. Almost every european driving license can be converted, US driving licenses can't.) Just bring your spanish license + translation to the local office when you arrive and get your own japanese license.