Mermaid's Forest(2003)

Mermaid's Forest follows Yuta, an immortal wanderer cursed for five centuries after consuming mermaid flesh. Based on Japanese legend, eating mermaid meat promises eternal life but more often brings death or transformation into a Lost Soul—a damned creature trapped between worlds. Desperate to break his curse, Yuta travels across Japan seeking a cure, encountering others whose lives have been similarly destroyed by the same dark magic. The series blends horror and dark fantasy as Yuta navigates a landscape of supernatural tragedy, where immortality becomes a prison rather than a gift. Each encounter reveals new layers of suffering and the terrible price of forbidden knowledge.