"Yami ni Naku Oni" is a manga series that blends elements of historical fiction, supernatural horror, and psychological drama. Set in feudal Japan, the story revolves around a cursed village plagued by a malevolent entity known as the Oni, a demonic figure that preys on the villagers' deepest fears and sins. The narrative centers on a young man named Haruto, a wandering swordsman with a mysterious past, who arrives in the village seeking refuge but soon becomes entangled in its dark secrets.

Haruto discovers that the Oni is not merely a mythical creature but a manifestation of the villagers' collective guilt and suppressed traumas. Each villager harbors a hidden sin, and the Oni exploits these vulnerabilities, driving them to madness or death. As Haruto investigates, he learns that the curse is tied to a tragic event from the village's history involving betrayal, murder, and a forbidden ritual gone awry. The ritual was intended to summon a protective deity but instead unleashed the Oni, binding it to the village and its inhabitants.

The story delves into the lives of key villagers, including Ayame, a young woman burdened by her family's dark legacy, and Jiro, a former samurai haunted by his role in the ritual's failure. Haruto's own past is gradually revealed, showing his connection to the Oni and his personal struggle with guilt and redemption. As the curse intensifies, Haruto must confront not only the Oni but also his inner demons, forcing him to make difficult choices that could either save or doom the village.

The manga explores themes of morality, the consequences of human actions, and the cyclical nature of vengeance. The Oni serves as both a literal and symbolic antagonist, representing the inescapable weight of past sins. The narrative is driven by a series of tense encounters, psychological battles, and revelations that unravel the complex web of relationships and betrayals within the village. The climax builds toward a confrontation between Haruto and the Oni, where the true nature of the curse and the possibility of breaking it are revealed.