If you want to own a personal vehicle in Japan, you have to purchase/complete:
The minimum amount required by U.S. Military Law is 30,000,000-yen for bodily injury and 3,000,000-yen for property damage. Insurance may be purchased from an authorized Japanese agency.
Japanese Compulsory Insurance (JCI):
It must be purchased by a company licensed in Japan. Japanese law requires vehicle owners to carry in their cars at all times a form certifying that the second type of policy has been purchased. A firm selling the policy issues the form. The Japanese government determines level of JCI coverage. Failure to maintain current Japanese Compulsory Insurance (JCI) for your POV will result in suspension or revocation of driving privileges for up to one year.
Owners will be required to get their vehicles a biennial safety inspection. The inspection is based upon Japanese safety standards. This is a requirement under Japanese law and is required for all A/E/Y plated vehicles. This requirement is for vehicle inspections to be accomplished every two years within 30 days of the JCI expiration date.