I have a 10 year old son who lived in the States until he was about 3 and a half. Then, we moved to my home country (Japan) where my parents are. When we first moved back, he had his American dad in his everyday life, but after a year or so, we split up. His dad hasn't really been in his life ever since and I've been working, so when he was in kindergarten, my mom was taking care of him, taking him to and picking him up from the kindergarten.
Being in a situation like this, he started learning Japanese more and more and started to forget English. Now at the age of 10, he does not speak English at all.
I am wondering if it is already too late for him to learn how to speak English again. What I assume would be difficult is, there wouldn't be enough occasions where he could actually use English since everybody aruond him is Japanese. So I thought maybe 'I' could start speaking to him in English. Do you think this will be any good? Or will this be just in vain...?
On a side note, I wonder if it's even appropriate for me to teach him English, considering it is not my first language, though I still think it would be nice to at least be able to communicate in English even with an accent.
Your advice would be very much appreciated!