To live in Japan you must have some form of health insurance from either the Japan National Health Insurance (NHI), which is available to all residents, or private insurance (Japanese or an international plan), or both. Many companies provide NHI to their employees, although they are not required to do so. If your health insurance is offered by your employer, a monthly fee will be deducted from your income. If you choose to buy into the program on your own (which can be done at your local ward office) you will receive a bill for the program three times a year (January, July, and October). Application with your ward office is simple (no appointment is necessary), and only requires your alien registration card and, for those that have been residents for less than a year, documentation (employee ID, contract, etc.) that certifies your period of stay in Japan will be greater than one year.
The NHI covers 70% of the costs associated with most medical care, requiring you to pay the remaining 30% before you depart the medical facility. Some use a combination of the NHI and private insurance as a supplement to allow for greater examination options (some tests – like mammograms – aren’t covered under the NHI, for example), or for broader treatment options. The costs for buying into NHI or having it deducted from your salary depend on a number of factors including your annual compensation and how many (i.e. family beneficiaries) are included in the program. While the costs naturally differ widely from person to person, the average expat should expect to pay approximately US$500 per month for NHI and Japanese government pension.
Some opt to go with private insurance as it affords expats more options because a number of the foreign clinics operating in Japan do not accept the NHI program, and because the NHI program is limited to Japan and does not provide coverage outside of Japan. With the premium private insurance companies you could conceivably spend around US$150 per month for full coverage.
Global Health (http://www.globalhealth.jp), from InterGlobal, is a private health insurer that caters to the expat community in Japan. They can also be contacted toll-free at 0120-36-0422. HealthOne (http://www.healthone.jp/) and MedOne (http://www.medone.jp/) are two other expat friendly insurance providers that operate in the Japanese market.