Shironagasu-tou e no Kikan

A late billionaire's will contains an unexpected summons to a place called Shironagasu Island. Acting on it is Ikeda Sen, a New York private detective, who travels to the island together with Nenekko Izumizaki, a young woman said to possess unusual abilities. Once they arrive, a string of strange killings begins to unfold around them, and the case pulls the pair toward whatever has been kept hidden on the island's grounds.