x-arthur_bgm.user.js

// ==UserScript==
// @name        [x-arthur.gree-pf.net] play back ground music
// @namespace   http://kid0725.usamimi.info
// @version     1.0
// @author      KID the Euforia a.k.a. blueberrystream
// @description play kakusan-sei million arthur's bgm
// @homepage    https://github.com/blueberrystream/userscripts/
// @match       http://x-arthur.gree-pf.net/*
// @grant       none
// @require     http://code.jquery.com/jquery-2.1.3.min.js
// @copyright   2015+, KID the Euforia a.k.a. blueberrystream
// @license     MIT License
// ==/UserScript==

void(function() {
    var V = 0.2,
        B = '',
        a = document.createElement('audio'),
        k = null,
        p = location.pathname,
        m = {
            '/mypage': '05.mp3',
            '/ability': '05.mp3',
            '/help': '05.mp3',
            '/present': '14.mp3',
            '/quest/boss': '06.mp3',
            '/quest': '03.mp3',
            '/raid': '12.mp3',
            '/arena': '21.mp3',
            '/guild': '14.mp3',
        };

    for (k in m) {
        if (p.indexOf(k) === 0) {
            a.src = B + m[k];
            a.volume = V;
            a.preload = true;
            $(a).appendTo('body').get(0).play();
            break;
        }
    }
})();