$(document).ready(function(event) {
      
      $('.jap').click(function() {
        $('#sb-arrow_left').css({ visibility: 'visible' });
        $('#sb-arrow_right').css({ visibility: 'visible' });
      });
      
      $('.norm').click(function() {
        $('#sb-arrow_left').css({ visibility: 'hidden' });
        $('#sb-arrow_right').css({ visibility: 'hidden' });
      });
});