It goes beyond the SIM card. Japan uses a totally different band for cell phone communications and only certain US phones and carriers work in Japan. You can check with your carrier. There are multiple other options including purchasing a very inexpensive phone with a SIM card that offers very low rates in Japan (Telestial.com). I bought one for $59 with the card. There are also companies that rent cell phones directly at the airport or they will deliver them to your hotel if you are traveling through Narita/Tokyo. When you are done with them, you can drop them in the mail to return them.