The Spring Palace is one of four rooms in Issei Tenkai's mansion connected to the fountain patio. From the entrance to the patio, it is the leftmost of the four rooms. In 2000, Tenkai used it during the finals of his confectionery design competition for building his own entry - a scene of a ship complete with water and a treasure chest, all made of chocolate - as a baseline for the other finalists. During judging, however, the body of Isaku Hyōdō, one of the finalists, was discovered inside the chocolate chest, leading to Tenkai's conviction for his murder. As well, Hyōdō contest entry, consisting of frozen sherbet sculptures of the signs of the zodiac, disappeared. Over 18 years later, Tsukasa Oyashiki, Tenkai's adopted daughter, opened the Zodiac Art Gallery inside the mansion, claiming