Case Closed (1996)

Season 9

Episode 4: And There Were No Mermaids (The Deduction)

Conan and Heiji investigate the area and history of Mermaids Grave, a forest on mermaid island. They learn that an elder who is over 130 years old is a holder of the arrow and the head of the festival. While investigating two more murders occur. Conan reveals to Heiji he knows who the murderer is and to meet him later, but later he and Kazuha fall off a cliff.