Case Closed (1996)

Season 9

Episode 3: And There Were No Mermaids (The Murder)

Conan along with Heiji, Ran, and Mouri visit the Isle of Mermaids looking for Saori, who had sent a letter to Heiji and Mouri asking them to save her from being killed by a mermaid, but when they try to look for her she has been reported missing. Every year on this island a festival is held were 3 locals win the Dungong Arrow that is said to wield immortality to its carrier. The festival is brought to a disastrous end when one of the winners is found dead hanging down the waterfall.