A small, lone Kappa miraculously survives over 200 years into modern day Japan, when he is found by young Koichi. Coo, who is secretly adopted by Koichi's family, searches with his new human friend for unpopulated places in hopes of finding any remaining of his kind.
Invited to a wealthy client's mansion, time-traveling witch Yuko and her companions arrive to find a group of collectors assembled to participate in a mysterious auction. And the mystery only deepens when the collectors go missing one by one. As more guests disappear and strange occurrences abound, Yuko and her friends realize they must solve the mystery before they vanish as well.
