"I learn Japanese for my next girlfriend."
Translation:Japanisch lerne ich für meine nächste Freundin.
That's right too - it's a question of emphasis.
In German you can take almost anything from your sentence, bring it to the front and invert verb and personal pronoun. This has the effect of stressing the thing you put at the front.
In this case the suggested translation sounds like the answer to a question like "Wieso lernst du aber Japanisch"?