I feel the same after a day full of speaking/writing English, Japanese and Dutch - afterwards I can't even think in German correctly anymore. ^^ツ≫?ケ But maybe that just means that you're doing it right, using other languages as often as possible so that you don't automatically think in German anymore. I don't know.
Woah, I never get how people manage to servive in Japan for so many years without speaking the language. Besides, I think it's rude. I mean, there are so many people who complain about immigrants who don't speak a country's official language, but they don't make any effort to learn a foreign language themselves when they emmigrate. : /
So, do you maybe have any tipps for learning efficiently when you don't have a tandem partner? : ) For example, I'd love to improve my listening skills, but I find it so hard to find Japanese online radios or interesting online streams offered by Japanese TV stations.