The cover you are required to carry and the cover you choose. 自賠責 is compulsory for every vehicle and 任意保険 is not, and what each pays for is different. Fire and earthquake cover on a rented flat, and what it actually pays out when the building moves. What travel insurance stops covering once you are a resident. Statutory health insurance and pension are a separate matter and live with tax.
This page does not yet list the offices, forms, costs or step-by-step procedures for it. The Immigration Services Agency publishes the Daily Life Support Portal, which covers this ground officially, free, in 19 languages, and is written by the agency that administers the procedures.
Everything on Locals is sourced from the body that publishes it, with the date it was read. That is slower than writing it from memory, which is why this page is empty rather than wrong. Back to Locals