"Tenjin" is a supernatural mystery anime set in a small, secluded village surrounded by dense forests and steeped in ancient traditions. The narrative centers on a young man named Haruto, who returns to his hometown after a decade-long absence following the mysterious disappearance of his older sister, Akari. Upon his arrival, Haruto discovers that the village is plagued by eerie occurrences, including unexplained deaths and sightings of shadowy figures. The villagers attribute these events to the wrath of Tenjin, a local deity believed to protect the land but also capable of unleashing curses if disrespected.

As Haruto delves deeper into the village's secrets, he uncovers a complex web of rituals, sacrifices, and long-buried grudges tied to the worship of Tenjin. He learns that his sister’s disappearance is connected to a forbidden ceremony conducted by the village elders, who sought to appease the deity by offering a chosen individual as a vessel for its spirit. Akari, possessing a unique spiritual affinity, was selected for this role, but the ritual went awry, resulting in her vanishing and the subsequent unrest in the village.

Haruto teams up with Rika, a childhood friend and local shrine maiden, who provides insight into the village’s traditions and the nature of Tenjin. Together, they confront the elders and uncover the truth about the deity’s origins, which are tied to a tragic historical event involving betrayal and vengeance. The story explores themes of guilt, redemption, and the consequences of tampering with forces beyond human understanding.

The plot intensifies as Haruto and Rika attempt to break the cycle of curses and free Akari from her fate. Their journey is fraught with danger, as they face not only the supernatural manifestations of Tenjin’s wrath but also the resistance of the villagers, who fear retribution if the rituals are disrupted. The series builds toward a climactic confrontation where Haruto must make a pivotal choice between saving his sister and preserving the fragile balance of the village’s spiritual ecosystem. The resolution leaves lingering questions about the nature of faith, sacrifice, and the cost of defying tradition.