- "So the school's a castle, and the students are slaves... It's so on point that it makes me laugh. This really is the inside of that asshole's head...!"
- —Ryuji Sakamoto, Persona 5
- Background Music: "King, Queen, And Slaves" (and its Another Version)
- Available: April 11 (tutorial), April 18 (mission)
- Deadline: May 2 (Protagonist, Ryuji and Mishima getting expelled)
- Owner: Suguru Kamoshida
- Location: Shujin Academy
- Keyword: Castle
A world within the Metaverse created by Suguru Kamoshida. The Palace transforms Shujin Academy into a castle, reflecting Kamoshida's belief that he is the king of Shujin Academy. The Palace is guarded by knight shaped shadows.
After Shiho Suzui's suicide attempt, the Phantom Thieves of Hearts plan a heist to steal Kamoshida's heart in order to prevent the protagonist's expulsion. Shadow Kamoshida initially imprisons the protagonist and Ryuji Sakamoto within, where they meet Morgana, who explains the other "students" in the jail cells and Kamoshida's harem are Cognitive existences who are not the actual person, but replicas born from how Kamoshida views the volleyball team-ie, as slaves to do his bidding and increase his prestige, or sex objects.
The protagonist and Ryuji accidentally enters the palace and is instantly spotted by Shadow Kamoshida, where he imprisons them in a cell in the palace dungeon. Awakening Arsene, the protagonist defeats a shadow appearing as 2 Jack-O-Lanterns, then they try to escape the palace and rescue Morgana in the process. As they escape further through the dungeon area, they will encounter a jail cell containing the cognitive existence of an abused volleyball student and fight off another Shadow appearing as 2 Pixies, then progress through the path until reaching a section of the main castle area and returning back to the real world.
At the second time around, the protagonist is allowed to explore the dungeon area fully, from a hole into the castle's main lobby then into the staircase where they first escaped from. Further into the dungeon area is the training hall of love. The first cell has the cognitive students being beaten by shadow guards. Another cell in the "training hall" contains volleyball team members that are subjected to running on a treadmill with a spiked rolling pin at the end. The last explorable cell contains a cognitive student being hung upside down and being hit by spiked explosive volleyballs from a cannon. When the three go back to the lobby, they are spotted by Shadow Kamoshida and he summons a guard that splits into 3 Bicorns to attack the protagonist and Morgana, then after they fail to defeat them, Ryuji will awaken and join the party into defeating the guard captain, which will appear as Eligor. The three then escape the palace a second time.
The third time entering the palace allows the protagonist to explore a part of the west building of the palace. However, the gate leading to the rest of the palace is closed so the 3 must enter the other gate, which leads to a candle-lit room which leads to the awakening of Ann. After defeating the guard captain that takes the form of Belphegor, the 4 are forced to escape the palace again since Ann is too tired and bewildered to continue.
The fourth time entering marks the full exploration of the palace itself. The group of 4 are allowed to explore the rest of the palace this time. Accessible from the central hall is the third floor of the east building which contains the library, which contains books that glorify Kamoshida, books about his lustful views of the female students of Shujin Academy including one titled: "Ann Takamaki, the Charming Doll," and books that contain the names of the male students of the academy, with one of them being a direct insult to Ryuji called: "Ryuji: The Vulgar Ape". Opening the hidden gate of the library by inserting the King Book, Queen Book and Slave Books allows the party to gain access to a room which is filled with pictures of Ann, and also contains one of Kamoshida's medals. The medal is required to open a gate to the annex, which contains a chapel containing a massive statue of Shadow Kamoshida and guarded by a shadow that manifests as Archangel, and leads all the way to the roof.
The roof is heavily distorted due to the nearby treasure and a silvery liquid can be seen seeping through the bases of the floor, and the distortions also forms cubes around it. Further through the roof area contains decors and pillars that consist of nude, headless and buxom female busts, further proving the castle owner's lustful nature. An elevator will lead the phantom thieves to a portrait of Kamoshida which leads to a shortcut to the lobby of the castle. The final area is the central tower, whose passage to the treasure room is locked by a series of swinging scythes. The switch to stop the axes from moving is also off, forcing the Phantom Thieves to find a key to open it. The Keys are actually the eyes of the statue and are held by 2 guard captains, both manifesting as Eligor. The first one is highly visible since it's the only captain in the area, while the second room containing the other eye has 3 captains, with only 1 holding the eye. The captain holding the eye is the one with the white aura as shown in the Third Eye. The eyes then must be inserted into the statue to activate the switch. After stopping the scythes, the upper level of the central tower can be accessed, which contains a guard captain manifesting as Mara (Torn King of Desire). After defeating him, it's a straightforward path and jumping on a bust statue will lead the Phantom Thieves to the last section: the throne room. Sneaking past the throne room leads to a gold trove that contains the formless treasure.
After the calling card is issued, the Phantom Thieves just need to go straight to the throne room, where the showdown with Shadow Kamoshida begins.
Kamoshida's Treasure in reality is his Olympic gold medal, which takes the shape of a royal crown in the Metaverse. The Phantom Thieves sell the medal to Munehisa Iwai for 30,000 yen and use that money to celebrate with a buffet at the Wilton Hotel in Shibuya. The player receives 6,000 of the remaining yen for their own personal use.
- Bicorn (Morgana's Awakening)
- Eligor (Ryuji's Awakening)
- Belphegor (Ann's Awakening)
- Suguru Kamoshida (Asmodeus)
- Trophy of Obsession
- Kamoshida's Palace is likely a reference to Yukiko's Castle. It has black-and-white checkered floors and a red carpet with gold edges. However, instead of a princess searching for her "prince", it is now a king searching for his queen.
- The way all male student prisoners are tortured with cruel physical training machines alludes to Michiko Matsudaira's abuse to two physically incapable male schoolmates (Kenta Yokouchi and Tsutomu Kurouri) in the Snow Queen Quest of Megami Ibunroku Persona.