Mementos is a location that is visited several times throughout Persona 5. Part of the mysterious Metaverse, it is the Palace of the collective unconscious. Located under the subway tunnels of Shibuya, it is lined with train tracks and train platforms that Shadows, the game's enemies, actually use to traverse the dungeon. As it would be infeasible to traverse the dungeon by foot, the shapeshifting Morgana transforms into a car and has the protagonist drive him when exploring it.
The Phantom Thieves are able to visit Mementos in order to take requests to change the hearts of people whose distortions are not bad enough to cause their own individual Palace to manifest. Exploring Mementos' randomly generated floors also offers the opportunity to gain money and EXP, as well as capture Personas that the player may have missed in a previous Palace. An entrance to the Velvet Room is conveniently located at the entrance to Mementos, allowing a player to summon or fuse new Personas.
As the Phantom Thieves' notoriety increases, they are able to explore more and more of Mementos. Mementos serves as the final dungeon of the game, as the team sets out to change the heart of society at large. They manage to reach the deepest depths of Mementos where they find the Holy Grail, an incarnation of Yaldabaoth, the God of Control. Yaldabaoth easily defeats the Phantom Thieves and merges Mementos with reality before being defeated by the Phantom Thieves for good.
Mementos has one main platform with a slant in the middle, similar to Meta Crystal, with two pass-through platforms over the centre and the left side. A third platform with a cracked screen occasionally appears on the right. Trains periodically appear in the background, the set below the stage being able to damage fighters. Occasionally, a large triangle-shaped wall appears at the top or on the sides of the stage. The trains and the walls will never appear at the same time. When players run through the stage, they'll splash purple ink-like liquid with each step.
The stage's main design, based on Persona 5, uses a predominantly red colour scheme, with star designs and black-and-white halftone motifs. If a song from Persona 4 or Persona 3 is playing, the colour scheme changes to yellow or blue respectively, the respective primary coolers for each game. The platforms change design to incorporate flowers and checkerboard patterns (for Persona 4) or clocks and triangular patterns (for Persona 3). Similarly, the backdrop changes to include rainbow-like streaks (for Persona 4) or a moon (for Persona 3). If Joker wins a match with these alternate designs, the victory pose screen and subsequent music change accordingly.
The Morganamobile occasionally appears in the background, dropping off the other Phantom Thieves of Hearts:
- Ryuji Sakamoto, codenamed Skull.
- Ann Takamaki, codenamed Panther.
- Yusuke Kitagawa, codenamed Fox.
- Makoto Niijima, codenamed Queen.
- Haru Okumura, codenamed Noir.