WARNING: The following contains spoilers for the Attack on Titan manga and anime.
Attack on Titan established itself as a shonen manga juggernaut almost a decade ago, but fans' excitement is now at an all-time high as both the manga and its anime adaptation are approaching their conclusions. The political intrigue, violent warfare and wild schemes have made Hajime Isayama's series a phenomenon, but it all had to start somewhere.
Isayama first tested out the concept with a 65-page one-shot manga. This one-shot was titled Humanity vs. Titans and is sometimes referred to as Attack on Titan Volume 0. Although Shonen Jump rejected the original story, this prototype for the series helped lay the foundation for what was to come.
Humanity vs. Titans' Story
This one-shot's premise is roughly similar to the current Attack on Titan. In this world, a devoutly religious group created the Titans as guardians of nature to prevent deforestation, pollution and strip mining from ruining the landscape. Over the course of a century, the nature-guardian Titans destroyed 80% of humanity, ruthlessly catching and eating any human they can find. By now, the survivors have holed up in a forest within a ring of densely-packed trees, taking advantage of the Titans' refusal to damage wildlife. This has bought humanity time, but can the human race ever hope to be free? Murakumo, the hero, thinks it's worth a shot.
Murakumo is deadly, cool and determined, which may remind viewers more of Levi Ackerman than Eren Yeager. Murakumo has a friend, Tsubaki, who implores Murakumo to train her so she can fight the Titans too. The two friends both lost their parents to these deadly giants, and before long, it's time to fight. Murakumo faces a Titan in mortal combat, becoming one himself (which resembles the Attack Titan) to fight it on even terms. Murakumo gives his life to destroy the Titan and save the town, and later, Tsubaki begins practicing her sword swings at Murakumo's grave to inherit the battle against those dreadful giants. The one-shot thus ends on a grim but also hopeful note.
How This May Tie Into Attack On Titan
A few elements from the one-shot were clearly dropped before the current Attack on Titan story began. The "protect nature from humanity" element is long gone, replaced by bloody international politics and the rise and fall of empires. There is far more at stake than protecting the trees in Attack on Titan, and the one-shot never suggests that there is anything more to the story than "humanity tries to survive the Titan onslaught." Still, the concept of a cornered humanity fighting the Titan apocalypse served as a fine hook for Attack on Titan's early days before the series' stunning reveal that there is a world beyond the walls.
Meanwhile, the one-shot clearly foretold Eren's status as the Attack Titan's wielder, though Eren wouldn't realize this power for himself until the battle for Trost. Eren's lone-savior complex is also similar to how the Murakumo character takes it upon himself to defend humanity with his incredible skills. Mikasa's friendship with Eren was also foretold in this one-shot, except that early on, it was Mikasa who protected Eren and not the other way around.
What might this one-shot tell us about Attack on Titan's future and its ending? The series has a few chapters left to go, but the one-shot has a definitive ending of Murakumo heroically sacrificing himself and passing the torch to Tsubaki. Fans may wonder if Eren will also become a sacrificial figure, either willingly or unwillingly, to end all war and bloodshed between Marley, Paradis Island and other players.
Eren is rapidly changing from hero to antihero to possible villain. His death might not just be likely but unavoidable, and it might also heal the world. If so, the one-shot makes a rather heavy-duty prediction, though the young Hajime Isayama had no idea at the time just what he was foretelling.