B has been pushing to speak more Japanese. He likes it, even though he doesn't know much. He finds it funny when he makes a mistake (the other day, he said, "mom is a fish" when he meant...actually I never did find out what he was trying to say). He's been saying this over and over.
We ended up speaking in not-quite-correct Japanese in front of my family. Only one of my aunts knows any Japanese so it feels a bit rude but I do want to practice. And it was the first time he has tried to have a conversation in Japanese without me coaching him or the teacher telling him to say it.
This morning we were walking to school and my son started speaking in Japanese. I explained to him that it isn't exactly polite to speak in another language in front of other people and since daddy doesn't know Japanese, we should speak in English. B's solution was that I should translate everything we say into French, to which my husband agreed. This made for an interesting conversation. Everything I said in French, I had to translate word by word into English because when you are 5, it's confusing that one word in one language is a phrase in another. Also, B kept asking me how to say things in Japanese and how to say things in French. I think we will keep the 'wait until he is 6 to teach him French' plan. (Especially as it's Daddy's job to teach him French, and high school French was a long time ago. It's going to be work).
In the meantime, I think we will continue practicing Japanese on the way to school but drop it when we go to other people's houses. This is the first time it's come up but I think it's a good problem to have.