Its a commuting contract, you won't need a work visa except for training which is handled by the company. After it expires, they wont renew it and you will enter japan with a crew permit, it bypasses the need for visas but its more limiting. I believe it's 7 or 9 days maximum and you are limited to the area of your port of entry, so technically, if you arrive in Narita, you can't go on a trip to Kyoto.
Sam10 and Catacroker, you guys have any updates regarding your screenings? Best of luck!