function japanese_fonts_available() {
  var half = document.createElement('span');
  var full = document.createElement('span');
  half.appendChild(document.createTextNode('\uFF71'));
  full.appendChild(document.createTextNode('\u30A2'));
  document.body.insertBefore(half, document.body.firstChild);
  document.body.insertBefore(full, document.body.firstChild);
  var havejapanesefont = half.offsetWidth != full.offsetWidth;
  document.body.removeChild(half);
  document.body.removeChild(full);

  return havejapanesefont;
}
document.observe('dom:loaded', function() {
  $$('.japanese-text').each(function(element) {
    var nextEnglish = element.next('.english-text');
    if (!japanese_fonts_available()) {
      element.innerHTML = nextEnglish.innerHTML;
      nextEnglish.hide();
    } else {
      element.title = nextEnglish.innerHTML;
      nextEnglish.hide();
    }
  });
});