Attack on Titan Volume 0

Chapter 0 is the official dub title for the draft story written by Hajime Isayama which would later evolve into Attack on Titan. The draft story had a very different setting, but certain aspects of the Attack on Titan world were already in place. It was released alongside the DVD version of the first volume of the anime on July 17, 2013.

Setting
Being an early draft of the series, most things about the world were quite different from the current story. People used to build their cities inside Forest of Giant Trees (instead of Walls) because it was noted by humans that Titans didn't harm wildlife, and consequently, wouldn't harm the trees.

The Military seems to only have two divisions, although only one is ever mentioned. The Vanguard seems to would have later evolved into the Survey Corps, as they are the ones actively fighting Titans.

Titans
The Titans themselves were part of a human extermination project led by scientists and religious groups. Titans were said to be vastly superior to any living being.

Instead of being in the nape of their necks, their weak spot was located in a place inside their bodies which varied from Titan to Titan. Attacking this weak point was fatal.

Titan Shifters were also present, and were shown to have already infiltrated the military. Somewhat similarly to their current counterparts, killing them was impossible while they were in their human form, and attempting this would trigger their transformation. Only hitting their weak spots in Titan form would cause their death.

Weaponry
Instead of dual sharp blades and the 3DMG, humans were only equipped with two flaming blades that were capable of shooting energy beams. It's also shown that soldiers are able to perform super-high jumps to attack Titans.

Characters

 * Private Murakumo (むらくも二等兵) is the protagonist and a Titan Shifter. He is similar in appearance to Mikasa and Ymir, and his Titan form is the same as Eren's, but unlike Eren, he knows at the start of the story he's a Titan Shifter. He claims to have joined the Vanguard to gain the strength necessary to protect his friends. He may be based on Hajime Isayama himself.
 * Tsubaki (つばき) is a little girl who seeks to become Murakumo's apprentice. She wants to become strong so she may avenge her parents who were killed by the Titans. She looks almost identical to Eren.

Story
The story begins in a somewhat desert area looking similar to the desert area in the attack on titan back story area is now it is later shown with that same titans eating the vanguard group as they are seen dead a man runs to the titan now feeding on the people the man jumps in the air but is killed by the titan. it then shows a person named murakumo who is looking around he then goes to a place where tsubaki is currently now. she begs him to train her so she can do reasons unknown but he insists to do not and talks with another soldier.

He then looks behind and says "its just like your father" and says practice by swinging your sword 100 times a day she then says if he applied to he vanguard corps to get revenge on the titans for reasons unknown but he then screams out wrong they are there to protect hes allies they sit quietly until he says don't forget this a person is looking at him strangly.

he is working hard until somebody called his name he stands in shock as he is surrounded they say he is suspected to be a titan they talk about the details and hints that he is the greatest military strength

after he says nothing they say what is wrong with you! he sheaths his sword from his sheath and shops one of the soldiers surrounding him he then amplies that this man was eating years ago and says that he is his father(tell me if im wrong)then a huge flash happens and the obese titan appears and strangly other titans appeared too the titans then started cannibliesing the obese titans people are shouting and screaming while the soldiers are waiting what is next until murakumo confronts the titans and tries killing one of them but loses half of his body in the mean time it then triggers hes titan form similer to eren yeagers and talks tsubaki into attacking them while he has full control over the titan he lacks the awareness of whats happening to hes body when he beats a titans until his/her nucleas was showing he did not notice his nucleas was showing as well, the titan was smart enough to bite the nucleas crushing it then making murakumo disappear which looked like his death but not fully confirmed tsubaki then confronts the titans in rage and strangly it shows her training we do not know if this is a flashback or not.