ldr_z_function.user.js

// ==UserScript==
// @name           ldr_z_function
// @namespace      knell
// @include        http://reader.livedoor.com/*
// @include        http://fastladder.com/reader/*
// ==/UserScript==
(function (){
  window.addEventListener("keypress", function (e) {
    if(e.charCode == 122 || e.keyCode == 90){ // z key
      setTimeout(function(){
        document.getElementById("right_top_navi").style.display = "none";
      },100);
    }
    return true;
  },true);
})();