Death Note 13: How to Read

Death Note: How to Read 13 is an encyclopedia-style guide to the Death Note manga series, including character bios, storyline summaries, interviews with creators Tsugumi Ohba and Takeshi Obata, production notes and commentaries, and a bonus: the pilot chapter of the manga.

Everything that is contained within this book is official, written by the original author and artist, and is considered canon across all spectrum of the Death Note universe. Included in it is a character card of L, which shows his real name.

The Japanese release also includes 5 finger-puppets that are seen in the Death Note series:
 * Kira
 * L
 * Misa Amane
 * Near
 * Mello