Life is full of surprises. Did you know that anyone can open an English language school in Japan? While most are started by people with some experience in teaching, there are no such requirements. No one will come to inspect your school to see how and what you are teaching. This will be bad news for a gentleman who wants to enroll in a good school, a sensible requirement for a language student, and wonders how he can check a school's credentials. He hopes there is an official organization that rates them and perhaps a publication listing these ratings. He will be disappointed. It appears that there are no standards, no investigative agency, no requirements for a license and, consequently, no general list of approved language schools compiled by these nonexistent organizations.
The best source of general information is the Consumer Center (Shohisha Sentaa) in the ward office of the ku where the schools he is interested in are located. This is where he can ask about them and, later, take any complaints. I don't think he should have high expectations. Without standards, it would be unrealistic to expect ratings. However, they can tell him where they are, when they were established and how many students are enrolled and teachers hired. A Japanese friend made an apt observation: It is hard to believe there are no regulations in spite of the fact that we have tons of English schools -- but then, that's probably why we have so many of them.
There is a book, "Japan Language School Guide," by Paul Abramson, published by Tokyo Central in 1993, ISBN 4-9900200-252-0, with all the information he would like to have plus a lot more on culture, travel, exchange programs, in fact just about anything relating to language study. It includes a six-language introduction and a list of schools teaching both English and Japanese throughout Japan. Unfortunately, it is out of print, but he can keep it in mind as he wanders through used bookstores. Although some of the 500 schools he lists will have closed and others opened, there is much valid information that would be helpful in selecting a school.