"Brocken Blood" is a manga series that blends elements of supernatural horror, action, and psychological drama. The narrative centers on a young man named Kakeru, who becomes entangled in a dark and violent world after encountering a mysterious girl named Saya. Saya is not an ordinary human; she is a "Blood," a being with supernatural abilities and a thirst for blood. Her existence is tied to a secret war between humans and Bloods, who are hunted by a powerful organization known as the Church.

Kakeru's life takes a drastic turn when he is attacked by a rogue Blood and saved by Saya. During the encounter, he is inadvertently infected with Saya's blood, granting him enhanced physical abilities but also binding his fate to hers. This transformation forces Kakeru to confront the harsh realities of the Bloods' world, where survival often depends on violence and betrayal. As he struggles to adapt, he learns more about Saya's tragic past and the Church's relentless pursuit of her kind.

The Church, led by fanatical zealots, views Bloods as abominations and seeks to eradicate them. Their methods are ruthless, employing advanced technology and trained operatives to hunt down and destroy Bloods. Kakeru and Saya form an uneasy alliance, driven by mutual survival and a growing bond. Their journey is fraught with danger as they face off against both the Church and other Bloods, some of whom harbor their own sinister agendas.

Throughout the series, the relationship between Kakeru and Saya evolves, with themes of trust, identity, and morality explored against a backdrop of relentless conflict. Kakeru grapples with his newfound powers and the moral implications of his actions, while Saya struggles with her dual nature as both a predator and a protector. The story delves into the origins of the Bloods, revealing a complex history intertwined with human experimentation and ancient secrets.

The manga is characterized by its intense action sequences, visceral violence, and a dark, atmospheric tone. The characters are frequently tested by their circumstances, with alliances shifting and loyalties questioned. As the narrative progresses, Kakeru and Saya uncover deeper layers of the conspiracy surrounding the Bloods, leading to a climactic confrontation that challenges their resolve and forces them to confront their own humanity.