WWW with special characters (japanese)

I'm trying to do something like:

 AudioClip nameClip;
 
 void Start(){
     string japaneseName = "ヨッシー";
     WWW www = new WWW("http://translate.google.com/translate_tts?tl=ja&q="+WWW.EscapeURL(japaneseName)); //should return MP3-file
     nameClip = www .GetAudioClip(true, true, AudioType.MPEG);
 }
 
 void Update () {
     if(!audio.isPlaying && nameClip != null && nameClip.isReadyToPlay){
         audio.PlayOneShot(nameClip);
         nameClip = null;
     }
 }

which doesn't work, but if I exchange "ヨッシー" with "hello world" it does. Also, if I do a Debug.Log("http://translate.google.com/translate_tts?tl=ja&q="+WWW.EscapeURL(japaneseName)); and put the output in a browser it works as well, but not in Unity.

What's wrong?