Finding himself in an art slump, Yusuke asks Ren to be his bodyguard while he draws inspiration from Mementos, only to receive harsh criticism on his piece. Meanwhile, Akechi asks for Ren's help in finding evidence against an art dealer named Akio Kawanabe, who he believes is into some shady practices. As Yusuke manages to get out of his slump thanks to encouragement from his friends, Ren discovers that it was Kawanabe's assistant committing crimes, allowing Akechi to arrest him. Receiving praise for his new piece, Yusuke declines Kawanabe's funding in order to pursue his own hope.

With Futaba now a part of their team, the gang try to help her improve her social skills by taking her to the beach. Futaba then explains what she learned about Wakaba's research on cognitive psience, leading the gang to believe it is related to Palaces, mental shutdown cases, and the man in the black mask. As Mementos expands with the Phantoms' increasing popularity, Morgana becomes uncertain over whether he is really human while Ann is troubled with problems with her model work.

The students of Shujin High unanimously vote for Akechi to appear as a guest speaker at the culture festival. Despite the clear danger to this, Makoto follows through with it to gain more information. On the day of the festival, Akechi reveals that he knows of the Phantom Thieves' identities, explaining that he awakened his own Persona while up against the man in the black mask. Offering to help clear their names, Akechi asks for the gang's help in triggering a change in Sae's heart with the group to disband afterwards.

As the gang try to figure out a way to reach the top floor of Sae's casino Palace, Soujiro, who discovers a calling card in Futaba's room, is under pressure from Futaba's uncle, who is demanding that he pay him money or else give up custody of her. Ren gets Akechi's help to dig up dirt on the uncle, only for him to accuse Ren of pushing him. When government officials come to question Soujiro, Ren and Futaba manage to assure them that Soujiro is a good guardian, after which they come clean to Soujiro about being Phantom Thieves.

Following a reunion with Arsene, who urges him to remember everything, Ren is captured by the police, leading to his present day interrogation by Sae. As the interrogation draws close to an end, Ren, recalling an important discussion with Morgana and Futaba, asks Sae to show his phone to Akechi as he makes his way towards the interrogation room. After running into Sae and being shown the phone, Akechi reveals his true intentions and shoots Ren, making it look like a suicide.

The politician who was the mastermind behind all of the cases has been successfully reformed by the Phantom Thieves. However, the public’s reaction was not as expected. In order to eliminate the world’s distortion and enforce the justice he believes in, Ren proceeds towards the final battle along with the Phantom Thieves of Hearts.