vndb-jp-titles.user.js

// ==UserScript==
// @name        vndb-jp-titles
// @namespace   https://vndb.org
// @description Search results in Japanese on VNDB
// @include     https://vndb.org/v/*
// @version     1
// @grant       none
// ==/UserScript==

(function() {
    var div = window.byClass('div', 'vnbrowse');
    var table = window.byName(div[0], 'table');
    var tbody = window.byName(table[0], 'tbody');
    titles = window.byClass(tbody[0], 'td', 'tc1');
    for (var i = 0; i < titles.length; ++i) {
        var a = window.byName(titles[i], 'a')[0];
        var jp = a.getAttribute('title');
        var en = a.textContent;
        a.setAttribute('title', en);
        a.textContent = jp;
    }
})();