"OneeChanbara Kurenai" is a manga series that expands on the universe of the "OneeChanbara" video game franchise, blending action, horror, and supernatural elements. The narrative centers on Aya, a skilled swordswoman and member of the Baneful Bloodline, a lineage of warriors cursed with demonic powers. Aya wields the Zanka, a powerful sword that requires her to consume blood to maintain its strength. Alongside her sister Saki, who also shares the Baneful Bloodline, Aya battles hordes of undead creatures known as "Zombie" and other supernatural threats.

The story begins with Aya and Saki working as bounty hunters, taking on missions to eliminate Zombie outbreaks while grappling with their cursed heritage. Their journey takes a darker turn when they encounter a mysterious organization experimenting with the undead, seeking to harness the Baneful Bloodline's power for their own purposes. As the sisters delve deeper into this conspiracy, they uncover unsettling truths about their lineage and the origins of the Zombie plague.

Aya is portrayed as a determined and stoic protagonist, driven by a sense of duty to protect humanity despite her own inner turmoil. Saki, in contrast, is more impulsive and emotional, often clashing with Aya over their methods and goals. The dynamic between the sisters is a central focus, exploring themes of family, sacrifice, and the burden of power. Supporting characters include Rei, a scientist with ties to the mysterious organization, and Kagura, a rival warrior with her own connection to the Baneful Bloodline.

The manga features intense action sequences, with Aya and Saki utilizing their demonic abilities and swordsmanship to combat increasingly powerful foes. The horror elements are prominent, with grotesque Zombie designs and a pervasive sense of dread. The supernatural aspects delve into the lore of the Baneful Bloodline, revealing its ties to ancient rituals and dark forces. The narrative builds toward a climactic confrontation with the organization, culminating in revelations about the sisters' destiny and the true nature of their curse.