Some times one can see following note on the auction sheet 自賠責離島用 (Jibaiseki ritō-yō), which means compulsory insurance for remote islands.
Compulsory automobile liability insurance is compulsory for all cars and motorcycles that run on public roads. However, if the car is registered in remote island? the insuarance amount is cheaper.
Currently, if the user's address on the vehicle inspection certificate is located in the mainland, the insurance premium is set at 27,840 yen for ordinary cars and 26,370 yen for light cars (both for 24 months). If this is placed on a remote island, it will be significantly different from 8,810 yen and 7,820 yen respectively. From this, it seems that it feels "cheaper" to have a vehicle inspection on a remote island compared to the mainland.
By the way, remote islands in compulsory automobile liability insurance are "islands other than the mainland (Hokkaido, Honshu, Shikoku and Kyushu) that are not accessible to or from the mainland via bridges or tunnels (excluding Okinawa Prefecture). ” (from the website of the Ministry of Land, Infrastructure, Transport and Tourism). A famous example is Enoshima (Kanagawa Prefecture), which is treated as the mainland although it is an island because it is possible to come and go by bridges.