code: function kansuji (num) {
  
    if (num === 0) {
      return '〇';
    } else if (num < 0 || 9999 < num) {
      return '';
    }
  
    var kurai = ('0000' + num).slice(-4).split('');
    var s = kurai[0] * 1;
    var h = kurai[1] * 1;
    var j = kurai[2] * 1;
    var i = kurai[3] * 1;
  
    return (s === 0 ? '' : s === 1 ? '千' : JNUM[s] + '千') +
           (h === 0 ? '' : h === 1 ? '百' : JNUM[h] + '百') +
           (j === 0 ? '' : j === 1 ? '十' : JNUM[j] + '十') +
           (i === 0 ? '' : JNUM[i]);
  }
docs: 漢数字 (0から9999まで対応)
  @method kansuji
  @param  {Number} num
  @return {String} suji