var chap_array = new Array(
    ["12 - Weakness",'12'],

    ["11 - Present",'11'],

    ["10 - Season - Moon Light - Postlude",'10'],

    ["9 - Season - Moon Light - Prelude",'9'],

    ["8 - A Guy's Circumstances",'8'],

    ["7 - Midsummer Cinderella",'7'],

    ["6 - Awakening",'6'],

    ["5 - Sleep",'5'],

    ["4 - Cute Person",'4'],

    ["3",'3'],

    ["2",'2'],

    ["1",'1']
);
for (var i=0; i<chap_array.length; i++) {
    document.getElementById('id_chapter_1').options[i] = new Option(chap_array[i][0],chap_array[i][1]);
    if (document.getElementById('id_chapter_2')) {
        document.getElementById('id_chapter_2').options[i] = new Option(chap_array[i][0],chap_array[i][1]);
    }
}