Students with the student visa will be able to get a mobile phone with a post-paid plan (subscription).
Japan mobile phone companies do not offer pre-paid plans.
If you are on a tourist visa, you will be unable to purchase a mobile phone and subscribe to a post-paid plan as proof of residence is required. However, you can rent a wi-fi data modem, sim card or a mobile phone from rental services such as http://www.globaladvancedcomm.com/
Posted in: Life in Japan