The Decagon House Murders

In 1986, Tsunojima Island was home to the Decagonal House, a strange mansion with a decagonal appearance. The genius architect who built the mansion, Nakamura Seiji, died mysteriously in the burnt-down main building, Aoyashiki. Six months later, seven members of the University Mystery Research Club visit Tsunojima, which has become a deserted island, for a training camp. Meanwhile, on the mainland across the sea, Kawaminami Takaaki, a former member of the Mystery Research Club, receives a lette…