How difficult is the language barrier when teaching in Japan?

Thank you for the question!

Applicants for the Assistant Language Teacher (ALT) position are not required to know any Japanese before applying. Although applicants are encouraged to study the language, many of those selected for the program go knowing very little or no Japanese at all.

Even if you do not possess strong Japanese language skills, ALTs team-teach with Japanese Teachers of English who will be able to assist if there are any issues with a language barrier.

-San Francisco JET Program Coordinator

The language barrier has never been too much of a problem while teaching. Japanese Teachers of English are generally well-studied and fluent in English, and by working together and communicating openly in class there are few misunderstandings. However, depending on the type of school (high school English teachers have more training than elementary school general teachers, for example), there may be differences in how you communicate. Some teachers are higher level than others, and ALTs have to adapt to whomever they work with. Most ALTs manage just fine, and usually pick up any necessary Japanese very quickly.
However, I have found that the barrier is more noticeable when it comes to students. Often their English is very low-level, and they may be intimidated to try talking to a native speaker. I find that being very friendly and open to mistakes helps them warm up and try it out, but also learning Japanese on your own makes you very approachable to students (as well as non-English teachers at your schools!) Good luck!