Attack On Titan: Inside Kou

If you read these you’ll completely understand the Attack on Titan world. Finally, the official Japanese guidebooks for the series, long-awaited by fans, are here! Attack on Titan: Inside Kou is the first of two.
It’s loaded with amazing visuals and must-read content including complete information on all 78 characters who fight the Titans as well as illustrations and explanations on the Titans.
Also included are the results of a character popularity poll and an interview with writer/illustrator Hajime Isayama as well as the director and voice cast members of the series' anime adaptation.
Contents

Colossus Titan Papercraft
Color Illustration Gallery
Prologue
Character Encyclopedia
Character Encyclopedia Part 1: 104th Training Corps
Character Encyclopedia Part 2: The Garrison
Character Encyclopedia Part 3: Survey Corps
Character Encyclopedia Part 4: Military Police Brigade
Character Encyclopedia Part 5: Keys to Unlocking the World
Songs of Resistance
An Illustrated Guide to Humanity's Weapons
The Many Tools of the World of Attack on Titan
Titan Files
Guide to the Story and Tactics of Attack on Titan
A History of Humanity's Resistance
Situation Report on the State of Humanity
Characters Popularity Poll
Analyzing Humanity & the Titans

Also check out Outside Kou.