The Band of the Hawk and their enigmatic leader Griffith continue winning battle after battle as their prestige throughout the kingdom of Midland grows. But their latest task is one that has seen failure from everyone who has attempted it: the subjugation of the impenetrable fortress of Doldrey. But with members like Guts—the captain of the Hawks' raiders who can easily fell 100 men with his gigantic sword—such tasks prove to be trivial. However, in the aftermath of the battle, Guts decides to leave the Hawks in order to pursue his own dream and bids farewell to his companions, despite Griffith's attempts to make him stay. This single event causes Griffith to lose his composure, and leads him to make a decision that will alter his and the Hawks' fates forever.

The Band of the Hawk has dwindled in the year since Guts left them on his journey to forge his own destiny. Unaware of their fate, Guts returns to the Hawks—now being led by his former ally Casca—after a rumor about them passes his way. Once the saviors of the kingdom of Midland, the Band of the Hawk are now hunted as they desperately fight for their lives while plotting to free their leader, Griffith, after he was imprisoned for committing treason. But the man they save is far from the Griffith they remember. Griffith is a shell of his former charismatic self after a year of continuous, horrific torture. No longer able to walk, speak, or even hold a sword, he has nothing but the small, strange trinket, the Crimson Behelit, that will not leave him. The entire Band of the Hawk want to rise to greatness once more, but how much are they willing to sacrifice to return to their past glory? It doesn't seem possible, but when Griffith's heart darkens and a solar eclipse blackens the sky, the Behelit offers a choice that will leave the Band of the Hawk with a blood-soaked fate that will haunt them for the rest of their days.

In the Kingdom of Midland, a mercenary named Guts wanders the land, preferring a life of conflict over a life of peace. Despite the odds never being in his favor, he is an unstoppable force that overcomes every opponent, wielding a massive sword larger than himself. One day, Griffith, the mysterious leader of the mercenary group Band of the Hawk, witnesses the warrior's battle prowess and invites the wandering swordsman to join his squadron. Rejecting the offer, Guts challenges Griffith to a duel—and, much to the former's surprise, is subsequently defeated and forced to join. Now, Guts must fight alongside Griffith and his crew to help Midland defeat the Empire of Chuder. However, Griffith seems to harbor ulterior motives, desiring something much larger than just settling the war...

"Mine has been a life of much shame." Tokyo, 2036 (Showa year 111): a revolution in medical treatment has conquered death... By means of internal nanomachines and the "S.H.E.L.L." system whose network controls them, human beings suffer no diseases, require no treatment for injuries, and are guaranteed a 120-year lifespan, free from illness. Yet this consummate social system warps the Japanese nation in a host of ways: unresolved economic disparities, ethical decadence resulting from deathlessness, grave environmental pollution, and the "Human Lost" phenomenon, in which people themselves, disconnected from the S.H.E.L.L. network, become malformed. Japan teeters wildly between two potential futures: civilization's restoration or its destruction. Atmospheric pollution suffuses "Route 16" in the Outside—the area outside the Route 16 beltway. Youzou Oba, who lives an idle, drug-saturated life, joins Masao Horiki, a mysterious man who associates with the drag-racing gangs, on an incursion Inside—the area within the Route 7 loop where the privileged class lives—only to be embroiled in a violent struggle. When he encounters a malformed sufferer of the Human Lost phenomenon, a "Lost," Youzou's life is saved by Yoshiko Hiiragi, a girl of mysterious abilities who belongs to the anti-Lost agency H.I.L.A.M., and he discovers that he himself also possesses extraordinary powers... Degradation and death. Life and hope. Buffeted by fate, a man tears himself apart and cries out. Rage. Sorrow. Pathos. Consumed by despair and bitter tears, Youzou Oba is himself transformed into a demon. A human lost... or a human who can find himself?