Demons have now become commonplace around the kingdom of Midland, which has fallen into chaos. The swordsman Guts still cannot stay in one place for long due to his demonic brand. He could always manage to protect himself when he was alone, but now he has the added challenge of protecting former Commander Casca, a shell of her former self who neither remembers nor trusts him. They never have a moment's rest with the constant threat of demons, and they need a place where Casca will be safe till they find a way to heal her. Their elf ally, Puck, tells of the mystical land of Elfhelm, which is supposed to be a safe haven from the demons that ravage the lands. Tired and with only a vague hope, they struggle on to find a place to live—and they still need to find those responsible for the madness they are forced to endure.

Now branded for death and destined to be hunted by demons until the day he dies, Guts embarks on a journey to defy such a gruesome fate, as waves of beasts relentlessly pursue him. Steeling his resolve, he takes up the monstrous blade Dragonslayer and vows to exact vengeance on the one responsible, hunting down the very man he once looked up to and considered a friend. Along the way, he encounters some unlikely allies, such as a small elf named Puck, and Isidro, a young thief looking to learn swordsmanship from the former mercenary. As the ragtag group slowly comes together after having decided to join Guts in his quest, they will face incredible danger unlike anything they have ever experienced before.

Across the desolate wilderness, resources are scant and survival is the utmost priority. Essential supplies are delivered through the network of zeppelins, relying on protection from mercenary crews piloting single-engine fighter planes. At odds with pirates and political conflict, these brave aviators provide the strongest guard to stability in such dismal lands. Kylie—a talented, hotshot pilot—serves with one such crew: the Kotobuki Squadron. Recruited to the group by her childhood friend Emma, her natural aptitude for flight makes her a key member. Armed with their Hayabusa fighter planes, the six-member squadron is hired to protect people, goods, and society as they continue to engage hardships in their complex world.

A short spin-off anime released on Kouya no Kotobuki Hikoutai: Oozora no Takeoff Girls! game app and YouTube. (Source: AniDB)