Treasure Isle is rumored to hide a vast bounty of gold said to be guarded by the legendary beast "Yamawara", which Kindaichi and other treasure hunters gather to search for. But the host is killed before the group even arrives, and a bloody slaying takes place during a time in which none of the people on the island could have done it. Will the island's mythical monster-guardian claim more victims?
Ningyo no Rakuin is a tactical horror RPG inspired by the works of Howard Phillips Lovecraft. Between the fanatical quasi-human tribesmen, the Deep Ones rising from beneath the waves, and the grad student from Miskatonic University, there are more references to the Mythos than you can shake a shoggoth at. The plot itself is fast-paced, centering first on surviving the dangers of the island and later on rescuing the main character's girlfriend from a particularly nasty fate involving an unnamed Elder God and a transformation into a fishy abomination. Elements of the storyline play out before and after (and sometimes during) each battle, and the interludes between battle chapters include a short summary of recent events leading up to the current plot point.