var chapter_list = new Array(
  ["Vol.01 Ch.001: A New Season","v01/c001"],
  ["Vol.01 Ch.002: This is Sakura","v01/c002"],
  ["Vol.01 Ch.003: Makiko's Situation","v01/c003"],
  ["Vol.01 Ch.004: Ohanami Panic!","v01/c004"],
  ["Vol.01 Ch.005: Heart Days","v01/c005"],
  ["Vol.01 Ch.006: Execute Project M!","v01/c006"],
  ["Vol.02 Ch.007: A Passing Encounter","v02/c007"],
  ["Vol.02 Ch.008: Let's Go to Jungle Kingdom!","v02/c008"],
  ["Vol.02 Ch.009: Confession","v02/c009"],
  ["Vol.02 Ch.010: Each Desire","v02/c010"],
  ["Vol.02 Ch.011: A Desire that Wants to be Told","v02/c011"],
  ["Vol.02 Ch.012: Melody of going towards the future","v02/c012"]
);

var total_chapters = 12;

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;