Summer Palace

The Summer 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 second room from the left. All four rooms contain a stream of water that leads to the fountain in the patio.

In 2000, during Tenkai's confectionery design competition, it was assigned to Yutaka Kazami for building his entry for the finals. However, Isaku Hyōdō, one of the other contestants, was murdered, and his entry, consisting of frozen sherbet sculptures of the signs of the zodiac, went missing. Tenkai was arrested and convicted for the murder. Over 18 years later, Tsukasa Oyashiki, Tenkai's adopted daughter, opened the Zodiac Art Gallery inside the mansion, claiming to have replicas of Hyōdō's sculptures. The Summer Palace was where the sculptures representing the signs of the summer months were displayed.

Murder investigation

 * Main article: IS-7 Incident

When it came time to judge the final entries, Tenkai asked Oyashiki to fetch more film for his camera. While she did so, he began judging with Kazami's entry. To Tenkai's surprise, he found Kazami's final entry lacking in both design and taste, unlike his previous entries. Meanwhile, Oyashiki heard a noise coming from the room containing Tenkai's entry, and discovered Hyōdō's body inside.

Prosecutor Manfred von Karma was placed in charge of the ensuing investigation, and he indicted Tenkai for the murder. He exerted so much control that even Tyrell Badd, the detective in charge of the case, was unable to investigate Kazami's room. Even so, Hyōdō's body and sculptures went missing during the investigation. Though the police claimed to have taken custody of the body, Gregory Edgeworth, Tenkai's attorney, figured out the truth, though he was unable to prove it in court, and lost the trial. The sculptures had been stolen by Oyashiki after she learned that Hyōdō was, in fact, a French sculptor named Paul Holic. The sculptures were stored in secret inside a freezer in Tenkai's mansion, where they remained for 18 years.

The truth resurfaces

 * Main article: The Inherited Turnabout

In 2019, Oyashiki bought Tenkai's mansion from his relatives and checked on the sculptures that she had stolen. To her surprise, she found Hyōdō's body hidden inside one of them. She decided to use this to lure out the real killer, and opened the Zodiac Art Gallery featuring the works of Paul Holic. While she claimed to have made replicas of Hyōdō's statues, in truth many of them were the real deal, though Oyashiki had sculpted the statues that had not been made or finished in 2000.

Knowing that the real killer would come to the gallery to check on the body that he had hidden, Oyashiki set up a poison gas trap. Kazami fell for the trap and was hospitalized, though he ultimately survived. An investigation ensued soon afterward involving Gregory's son Miles. Oyashiki smuggled the statue containing the body to the "Summer Palace" and dumped it into the stream there. The body eventually thawed and resurfaced in the fountain, finally proving Gregory's claim from 18 years ago. Despite Oyashiki's efforts, Miles Edgeworth figured out that she had smuggled the statues using a lift trolley, covered in a tablecloth to look like a tea cart, which she had used to serve people tea. This in turn revealed Kazami as the real killer from the IS-7 Incident.