Shingeki no Kyojin Volume 0
The prototype of the original manga drawn by Isayama Hajime when he was 19 years old for the "Magazine Grand Prix" in 2006. Note: Bundled with the limited edition of the anime's first season Blu-ray/DVD disc 1 on July 17, 2013.
Shingeki no Kyojin Gaiden: Kuinaki Sentaku