If you are an ESL teacher, you know that many Japanese can not speak English well even though they study English at junior and senior high school for 6 years. The main reason is follows.
The occupation period was short
The 1st reson is literally.
Japan was occupied by the United States after the Pacific War. However, the United States did not enforce English education. After that, Japan fulfilled independence.
English education system was not for communicate
In Japan, English education was just an examination subject, not for communicate. Therefore, there were many English teachers can not speak English well. Of course their students will not be able to speak English.
It was not necessary for many Japanese people
The 3rd reason is core of this theme.
Fortunately, Japan had a strong economic power for a long time. And domestic economic scale is also quite large. Therefore, many people did not have to look overseas.
However nowadays, the English communication skill become important also in Japan.