If they have been in Japan for 15 years, keep getting 1-year visas, and want to stay in Japan long-term, they should speak to a lawyer. There are various criter

If they have been in Japan for 15 years, keep getting 1-year visas, and want to stay in Japan long-term, they should speak to a lawyer. There are various criteria that decide how long a visa you get, and while they aren't explicit there are things you can do to make it much more likely you'll get a long visa. At my first job I was a "contract employee", which was a much less stable position than I realized when I signed up, and I couldn't get more than a one-year visa either. Later I changed jobs and became a full employee and got a 5-year visa without issue.