自从超大型巨人出现，人类的和平与幻想被打破的那天开始，艾伦·耶格尔无尽战斗的日子就未曾中断……。
毫无抵抗之力，眼睁睁看着母亲成为巨人的饵食，发誓将巨人一个不剩地从世上驱逐的艾伦。
但，在残酷战斗的途中，他自己也变成了巨人的姿态——。
为了夺回人类的自由而驱使巨人之力的艾伦，在席纳之墙的史托黑斯区与“女巨人”交锋。这场巨人之间的激烈战斗，由艾伦艰难地取得了胜利。
即使如此，艾伦以及人类也没有休息的时间。下一场战斗已经宣告开幕。面对逼近罗塞之墙的大群巨人，人类将如何对敌！？

During the early 1930s in Chicago, the transcontinental train, Flying Pussyfoot, is starting its legendary journey that will leave a trail of blood all over the country. At the same time in New York, the ambitious scientist Szilard and his unwilling aide Ennis are looking for missing bottles of the immortality elixir. In addition, a war between the mafia groups is getting worse. On board the Advena Avis, in 1711, alchemists are about to learn the price of immortality. Takes place in the same universe as Durarara (2010).

Break-dancing but fierce warrior Mugen has to deal with the cold-blooded and conceited Jin, a samurai who believes he is above all. These sworn enemies are brought together by Fuu for a special task.