I'm french, living in France.
when I "think" it's usually wordless, concept, I just know what I think or what I want to do without having to "speak out" loud or in mind. (I think lot of people speak out loud when they are alone, speaking to themselves, I never do that!)
I don't speak to myself as in "speaking to me in attempt for a reply" or in "giving me orders to do things" like "ohhh, now let's go wash the dishes !" that sounds dumb to me.
If I speak in my mind, it's often with an imaginary other person, either repeating what I'll say for real, or having remorse and imagining what I could have tell that person instead, re-enacting an old scenes/discussion I had with someone, or preparing in mind what I'll write here on the forum.
when I "speak in my mind", it's mostly in french (mother tongue), like 80% (or less) I'd say.
and sometime 20% (or probably more, because I spend lot of time on this forum
) in english, it's like a second nature.
I can think in english even when not having to use it, but I usually "switch my brain" to english when I have to interact with english environment. Forum, or english person I talk to in real life, at work, etc. I tend to want to try to speak in english to foreigners, like they would understand better than french. not always the case haha. I wonder if my accent...
1% japanese? because why not! few words or expressions. I like the "kore wa kore, sore wa sore" expression. ("this is this, that is that", meaning "that's completely different things, don't compare them together!")