Betrayals are committed as Ruruka Ando struggles to survive and the traitor is close to being revealed. Monaca Towa's prophecy comes true when Kyoko Kirigiri's NG code is violated, because of Makoto Naegi. To bring an end to this dreadful game of despair, Kyosuke Munakata decides it's time to decide whose hope is better: his or Makoto's.
After Monokuma gives a short summary of the story thus far, the episode begins where the last one left off, with the Future Foundation building starting to collapse. As a horrified Yasuhiro Hagakure looks on, fearing that everyone in the building is dead, the tremors are felt by Juzo as he throws Ruruka off of him. Deciding that it won't matter once he escapes, he finally forces open the secret entrance in the library, only to find a dead end, revealing them to be under the ocean.
Elsewhere in the building, Kyoko is revealed to have reached the same conclusion, but for a different reason. She tells Ryota Mitarai that they aren't even in the same building anymore. When the unknown attacker knocked out the branch heads with sleeping gas, they brought the group to an identical room in an underwater facility, hidden under the Future Foundation headquarters. Kyoko first realized this when she noticed that the door of the meeting room lacked the damage from Sonosuke Izayoi's thrown knife, and she now believes that the sheer scale of the deception made it more difficult for everyone to believe.
When Ryota wonders why the group was brought underwater in the first place, Kyoko notes that it was likely to make it harder for outside forces to rescue them. However, this revelation has also made her suspect the identity of the attacker: Kyosuke Munakata. As one of the people supervising the construction of the building, he would've not only noticed the subtle change in location immediately, but that he would have been aware of the underwater facility; moreover, the entire situation seems to be moving things in his favor.
Elsewhere, Kyosuke continues his battle with the robotic doppelganger of Miaya Gekkogahara. Having taken extensive damage, the robotic puppet switches into "elimination mode", gaining back-mounted tentacles and missile launchers and replacing her arms with blades. Her renewed assault is quickly countered by Kyosuke, who reflects on how despair has taken everything from him. To spare anyone else from suffering the same fate, he renews his determination to destroy despair no matter what.
As the smoke clears from his last attack, he sees a PDA embedded in Miaya's exposed chest, displaying the profiles and NG Actions of each Future Foundation member. Justifying his actions as a means to "become hope", Kyosuke tears the PDA from the robot girl's chest before cutting her in half with his sword to finally deactivate her. As he is finally rejoined by Juzo, Kyosuke muses that he will achieve his aims no matter who he has to sacrifice.
Ryota is still trying to comprehend the possibility of Kyosuke being the mastermind of the Final Killing Game, but Kyoko promptly changes the subject towards finding Makoto. Ryota is skeptical of what the Ultimate Hope can do in this situation, but Kyoko states that Makoto can become stronger than anyone when the need arises; his optimistic nature allows him to believe in his friends no matter the cost to himself. Ryota seems to react to this as Kyoko explains that Makoto's ability to believe in others and never lose hope is both his greatest flaw and his greatest strength. Before she can elaborate, Makoto and Aoi arrive behind her, Makoto blushing and Aoi grinning as they had overheard Kyoko praising Makoto.
After explaining that Byakuya is attempting to come to their aid, Makoto becomes depressed, recalling Komaru's warning that someone would die because of him. He admits that he feels helpless to do anything in this situation, believing that Kyosuke may be correct in saying that his words have no power anymore. In response, Kyoko removes her glove to take Makoto's hand, reminding him of how his words inspired her and their classmates to fight off despair in the School Life of Mutual Killing. She assures Makoto that his friends are behind him after "catching" his hope, and that his best trait has always been his slight optimism.
Elsewhere, Juzo is slowly being unnerved by Kyosuke's stoic silence, despite him pointing out his serious injuries and the deaths of several more branch heads. Kyosuke grimly states that he personally killed Tengan, shocking Juzo momentarily before he tries to justify it as his friend's ascent to Chairman of the Future Foundation. He reaffirms his willingness to help Kyosuke change the world, prompting Kyosuke to reminisce on his long friendship with Juzo and Chisa Yukizome. Musing that he still believes that he can change the world for the better, he admits that he could never have come this far without his friends' support.
Juzo begins to tell Kyosuke something, but the former Ultimate Student Council President silences him by impaling him through the stomach with his sword. Stunned and betrayed, Juzo can only ask why, but Kyosuke coldly tells him that he knows the reason before leaving the former Ultimate Boxer to die. As he stalks down the hallway, he snarls that "Despair" will pay for making him kill his best friend. Unbeknownst to Kyosuke, his latest murder was witnessed by Ruruka, who had been hiding around the next corner before making her escape.
Makoto's group reviews the deaths thus far, with Makoto himself bringing up the message Tengan wrote in his own blood: "I entrust the hope of the world to you." Ryota glares at his phone, muttering "I can't keep..." to himself.
Ruruka collapses in a hallway, musing that Juzo was a fool for trusting Kyosuke. As she staggers to her feet and continues down the hall, she remembers the last time she saw Sonosuke alive: he had moved the bookshelf back over the secret exit to ensure that no one could violate Ruruka's NG Code. He assures his girlfriend that he set plenty of traps in the room to further deter intrusion, insisting that he values Ruruka's life even above his own. Ruruka admits she knows that before going for a kiss; however, she uses the moment to slide a candy into Sonosuke's mouth with her tongue. As the former Ultimate Blacksmith's bangle begins injecting its poison, Ruruka tearfully explains that she's making sure that Sonosuke can never betray her by betraying him first, even though she knows it's wrong of her to do so. In his final moments, Sonosuke only kisses Ruruka again before telling her that he doesn't consider her actions to be a betrayal and reaffirms his love for her.
While slowly building a barricade over another exit door, Ruruka trips over a piece of debris. Lying on the floor, she weakly insists to herself that she's not lonely, and that she can make plenty of friends once she escapes the Final Killing Game, even without Sonosuke. As time ticks down for the next sleeping period, she tearfully insists that she won't die, even on her own, and that she would live forever.
With minutes left before the bangles inject their sleeping drug, Makoto and Ryota attempt to block the door with a large piece of furniture - embarrassingly, Aoi promptly does it for them with ease. Looking pensively at her bangle, Kyoko notes that this doesn't ensure their safety, with Ryota adding that the attacker has complete control of the facility. Kyoko tells Makoto that no matter what happens next, he must never give up on hope and that she will always be at his side. Makoto announces that he'll do his best to make sure that they win the game before the time expires, putting everyone to sleep once more.
During the sleeping period, Ruruka is brutally massacred by the attacker, being slashed and stabbed all over her body in addition to having candy stuffed in her mouth. Makoto, Aoi, and Ryota awaken, relieved to be alive, but their joy quickly fades when they notice Kyoko's lifeless body, with blood dripping from her left eye. To their horror, the former Ultimate Detective's bangle has activated its NG Code: "Passing the fourth time limit with Makoto Naegi alive."
A distraught Makoto wonders why Kyoko didn't say anything about her forbidden action as Aoi weeps openly; Ryota curses that this can't be happening, but their mourning is interrupted when Kyosuke addresses Makoto over the PA system. Asking if Makoto has discovered Kyoko's NG Code and realized the futility of his platitudes, he announces that it is time for them to determine whose vision of hope is strongest.
The following are in order of appearance
- Yasuhiro Hagakure
- Ruruka Ando
- Juzo Sakakura
- Ryota Mitarai
- Kyoko Kirigiri
- Miaya Gekkogahara (Robot)
- Kyosuke Munakata
- Usami/Monomi (Voice Only)
- Makoto Naegi
- Aoi Asahina
- Byakuya Togami (Mentioned)
- Seiko Kimura (Mentioned)
- Kazuo Tengan (Mentioned)
- Koichi Kizakura (Mentioned)
- Chisa Yukizome (Mentioned)
- Sonosuke Izayoi (Flashback)
- Kazutaka Kodaka's favorite in this episode is when Kyoko took her glove off to hold Makoto's hand.