"Higurashi no Naku Koro ni Oni" is a manga adaptation of the "Oni" arc from the visual novel series "Higurashi no Naku Koro ni." The story is set in the rural village of Hinamizawa during the summer of 1983 and explores themes of paranoia, trust, and the fragility of human relationships. The narrative centers on Keiichi Maebara, a newcomer to the village who befriends a group of girls—Rika Furude, Mion Sonozaki, Rena Ryugu, and Satoko Houjou. The group often spends time together playing games and enjoying the peaceful village life. However, beneath the surface, Hinamizawa harbors dark secrets tied to its annual Watanagashi Festival and a series of mysterious deaths and disappearances.

As the story progresses, Keiichi begins to notice unsettling behavior from his friends and villagers. Paranoia sets in as he uncovers fragments of the village's dark history, including the curse of Oyashiro-sama, the local deity, and the involvement of the Sonozaki family, who wield significant influence in the community. Keiichi's trust in his friends erodes, leading to a breakdown in his mental state. The narrative delves into his descent into madness, fueled by suspicion and fear, culminating in a violent confrontation that reveals the tragic consequences of mistrust and isolation.

The "Oni" arc serves as a psychological thriller, emphasizing the fragility of human connections and the destructive power of paranoia. Keiichi's perspective dominates the narrative, offering a firsthand account of his unraveling psyche. The supporting characters, particularly Mion and Rena, play pivotal roles in both reinforcing and challenging Keiichi's perceptions, adding layers of complexity to the story. The arc also ties into the broader "Higurashi" narrative, providing insight into the cyclical nature of the tragedies in Hinamizawa and the interconnected fates of its residents. The manga adaptation retains the tension and emotional weight of the original story, presenting a gripping exploration of trust, fear, and the human condition.