var chap_array = new Array(
    ["15 - Love, Once Again",'15'],

    ["14 - Family",'14'],

    ["13 - Truth",'13'],

    ["12 - Wish",'12'],

    ["11 - Yukito",'11'],

    ["10 - Answerless Day",'10'],

    ["9 - The First Wave",'9'],

    ["8 - Once Again",'8'],

    ["7 - Misuzu",'7'],

    ["6 - Summer Festival",'6'],

    ["5 - Everyone Friends",'5'],

    ["4 - How to Make Friends",'4'],

    ["3 - Sky and Magic",'3'],

    ["2 - Our House",'2'],

    ["1 - The Beginning of Summer",'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]);
    }
}