var chapter_list = new Array(
  ["Vol.01 Ch.001: Visitor","v01/c001"],
  ["Vol.01 Ch.002: Pirates","v01/c002"],
  ["Vol.01 Ch.003: Satellite Attack","v01/c003"],
  ["Vol.01 Ch.004: Conformer","v01/c004"],
  ["Vol.01 Ch.005: Izanagi","v01/c005"],
  ["Vol.01 Ch.006: Wielder","v01/c006"],
  ["Vol.02 Ch.007: Meeting","v02/c007"],
  ["Vol.02 Ch.008: Phosphorescent Guardian Blade","v02/c008"],
  ["Vol.02 Ch.009: Attack! Special Envoy Squad","v02/c009"],
  ["Vol.02 Ch.010: Traitor Kisurin","v02/c010"],
  ["Vol.02 Ch.011: Man of the Sea Disembarks!","v02/c011"],
  ["Vol.02 Ch.012: Time-spinner Clair (First Part)","v02/c012"],
  ["Vol.02 Ch.013: Time-spinner Clair (Last Part)","v02/c013"],
  ["Vol.02 Ch.014: Evil God","v02/c014"],
  ["Vol.02 Ch.015: Time is like a Wave","v02/c015"]
);

var total_chapters = 15;

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;