auto_muji_sort.user.js

// ==UserScript==
// @name           AutoMujiSort
// @namespace      http://www.milk1000.cc/
// @include        http://www.muji.net/store/cmdty/section/*
// ==/UserScript==

(function() {
    var OLD_PATTERN = { sort: 4, count: 12 };
    var NEW_PATTERN = { sort: 0, count: 150 };

    var $ = function(selector) { return document.querySelector(selector); };

    if ($('select[name="sort"]') && $('select[name="sort"]').value == OLD_PATTERN.sort &&
        $('select[name="count"]') && $('select[name="count"]').value == OLD_PATTERN.count) {
        $('select[name="sort"]').value = NEW_PATTERN.sort;
        $('select[name="count"]').value = NEW_PATTERN.count;
        (typeof unsafeWindow != 'undefined' ? unsafeWindow : window).sort();
    }
})();