var chapter_list = new Array(
  ["Vol.01 Ch.001","v01/c001"],
  ["Vol.01 Ch.002","v01/c002"],
  ["Vol.01 Ch.003","v01/c003"],
  ["Vol.01 Ch.004","v01/c004"],
  ["Vol.01 Ch.005","v01/c005"],
  ["Vol.01 Ch.005.1: Omake: My Happy Way of Life","v01/c005.1"],
  ["Vol.01 Ch.005.2: Omake: The Rabbit of 10:30AM","v01/c005.2"],
  ["Vol.01 Ch.005.3: Omake: The Cat in Boots","v01/c005.3"],
  ["Vol.01 Ch.005.6: Epilogue: 16 years old","v01/c005.6"]
);

var total_chapters = 9;

for (var i = 0; i < chapter_list.length; i++) {
  document.getElementById('top_chapter_list').options[i] = new Option(chapter_list[i][0], chapter_list[i][1]);
  document.getElementById('bottom_chapter_list').options[i] = new Option(chapter_list[i][0], chapter_list[i][1]);
}
document.getElementById('top_chapter_list').value=current_chapter;
document.getElementById('bottom_chapter_list').value=current_chapter;
var current_chapter_index = document.getElementById('top_chapter_list').selectedIndex;