"Shin Ringetsu" is a supernatural mystery anime that revolves around a small, isolated village shrouded in ancient traditions and dark secrets. The narrative centers on a young man named Haruto, who returns to his ancestral home after receiving a cryptic letter from his estranged father. Upon arrival, Haruto discovers that the village is governed by a mysterious ritual tied to the lunar cycle, known as the "Ringetsu Ceremony," which is said to maintain the balance between the human world and the spirit realm. The ceremony involves selecting a "sacred vessel," a villager who must undergo a series of trials to appease the spirits and prevent calamity.

Haruto's return coincides with the disappearance of several villagers, including his childhood friend, Aya. As he investigates, he uncovers a web of lies, forbidden relationships, and long-buried tragedies. The village elders, led by the enigmatic priestess Sayuri, are deeply involved in maintaining the ritual, but their motives are increasingly questionable. Haruto learns that the spirits, once benevolent, have grown vengeful due to past transgressions, and the ceremony may no longer be sufficient to contain their wrath.

The story delves into themes of sacrifice, guilt, and the consequences of tampering with forces beyond human understanding. Haruto's journey is marked by encounters with both human and supernatural adversaries, including the restless spirits of those who failed the ceremony and the shadowy figure of the "Moonlit Wanderer," a being said to guide the chosen vessel to their fate. As Haruto pieces together the truth, he must confront his own family's role in the village's history and decide whether to uphold the ritual or challenge it to save those he loves.

The main characters include Haruto, a determined yet conflicted protagonist; Aya, whose disappearance serves as the catalyst for the plot; Sayuri, the priestess whose loyalty to the ritual masks a tragic past; and the Moonlit Wanderer, whose true nature remains ambiguous until the climax. The interplay between these characters drives the narrative forward, blending personal drama with supernatural intrigue. The story builds toward a climactic confrontation during the next Ringetsu Ceremony, where the fate of the village and its inhabitants hangs in the balance.