The Mermaid's Necklace
(人魚の思い出, Ningyo no Omoide
, lit. Mermaid's Memory) is an event in Tomba!
Bring the lost necklace to the mermaid in the Haunted Mansion. The mermaid can be found on the south side of the mansion close to the entrance of the Forest of 100 Flowers.
Speak to the Mermaid to activate the event.
The necklace can be found in a chest right to the 10,000 Year Old Man's hut in Trick Village. Return and give her the necklace to complete the event.