The Challenge (Rebellion) of Eden (エディンの挑戦（リベリオン）, Edin no Chōsen (Riberion)) is the ninth episode of Hyperdimension Neptunia: The Animation. It was first aired in Japan on September 6, 2013.
Neptune tries to wakes up a sleepy Plutia. She grabs her pillow and accidentally hurls it on the Peashy doll, so she walks up and puts it back. On the way out the door, she sees Nepgear and tells her that they'll be leaving for patrol in half an hour.
Compa and IF are conversing with Uni on the computer. They're all surprised how Neptune are patrolling all day with Nepgear and Plutia. When asked why she's in Lowee, Uni tells the two that she's helping Rom & Ram. They apparently found Peashy's location using Lowee's satellite imagery program.
While patrolling, Neptune spots a pack of wolves. Nepgear convinces her sister that the wolves won't make it to town, but Neptune says otherwise and charges against the monsters.
Compa and IF meets up with Uni, Rom, and Ram. Using the data they gathered, they find the apartment Peashy was last seen in. Since Neptune and Nepgear aren't with them, they plan to surprise them by bringing Peashy back to the Basilicom. They come across an apartment room and discover that it's left open, so they go inside. Inside, a bunch of posters that contains the same message, a protest against CPUs, that Compa and IF got before are everywhere.
Somewhere, Rei expresses her hatred towards the CPUs but only sees herself as a social activist. Questioning Anonydeath why he drag her along, he says that a certain client told him to. He says that he only spoke with the client on the phone but that the pay only matters. Rei tries to leave, but Anonydeath marks her as an accomplice, saying that she's the one who kidnapped Peashy. On the monitor, Peashy is shown to be absorbing light-colored orbs from tubes that are attached to her body.
Neptune and Nepgear are busy handling the wolves, but Plutia just sits out. Neptune asks for help and says that she's also doing it for her, but Plutia sees otherwise and thinks that Neptune is doing it for herself. Plutia transforms into HDD form and scares the wolves away. She plans to punish Neptune, ending with them fighting. Neptune tries to make Plutia stop and ends up deflecting her weapon. Neptune reverts back into her human form and begs Plutia to stay as her friend. However, Plutia tells her to stop lying to herself and that she has someone else she needs to do something for. Neptune laments and regrets about how she should have spent more time with Peashy. Neptune breaks into tears, but Plutia comes and comforts Neptune. Suddenly, Nepgear receives a call from Histoire, who informs them that a new nation has been formed.
Histoire informs Compa, IF, Uni, Rom, and Ram that a new nation has been formed in R-18 Island, and Nepgear, Neptune, and the other CPUs will come and investigate it.
Flying their way there, the latter arrives in R-18 Island. They suddenly stop after artillery guns aim at them, but it only fires yellow balloons in their direction. Anonydeath welcomes the CPUs to the newly formed nation, Eden. As Noire questions Anonydeath, Plutia spots Rei running within some forestry. When Noire questions that Anonydeath should be in prison, he says that they only met his double. Noire plans to take him down, but Anonydeath states that even she doesn't have jurisdiction to do that in Eden. Noire retorts that Eden doesn't even have a CPU and aims her weapon at him. Suddenly, a yellow-haired in a white suit falls on Noire. The girl introduces herself as Yellow Heart. Noire asks the CPU to get off her so that she can take Anonydeath down. Yellow Heart's demeanor then becomes serious and punches Noire with amazing strength. The other attack her, but she was barely fazed. Then she draws three-bladed claws from her hands and attacks the other CPUs.
Plutia spots Rei, who is talking to herself, and asks her about the cannon. Rei denies her involvement with the cannon and leaves, but she's stopped by a transformed Plutia, who says that Rei is full of lies. In the air, Neptune battles Yellow Heart, who is barely fazed and says that she's having fun, until she spots Plutia interrogating Rei and stops her. The two battle, but Peashy defeats Plutia with ease. Neptune, Vert, Noire, and Blanc surrounds Yellow Heart and attack her with their signature moves, plunging Yellow Heart in the water. Noire then spots Anonydeath, who turns off a device in his hand. Peashy emerges from the water and calls for her "Mama" and "Papa." Rei, the "Mama," and Anonydeath, the "Papa" appears and praises Peashy. Neptune flies down to her and asks why she's with them, but Peashy tells her to go away and that she hates anyone who hurts her Mama and Papa. Out of disbelief, Neptune demands what Anonydeath had done to her, but he says that he's only an emissary for Peashy, who he declares as the CPU of Eden. Then Rei announces that Eden demands the rights to export adult goods manufactured in the country to all nations in unlimited quantities, and non-compliance will result as a declaration of war. As soldiers surround them, Noire interjects that they lack shares due to being a newly formed nation, but Anonydeath dismisses what she said and says that the turn of events is exciting.
- Eden has been formed in R-18 Island as a new nation in Gamindustri.
- The CPU of Eden is revealed to be Yellow Heart.
- It is revealed that Yellow Heart is actually Peashy.
Rei produces the wrong paper and announces it to the CPUs when Anonydeath and she were announcing Peashy's reign as the CPU of Eden.
The setting starts off at Planeptune, where Neptune tries to wake up Plutia. Compa, IF, Uni, Rom, and Ram finds Peashy's last known location in an apartment containing posters with messages protesting against the CPUs. The Hearts and Nepgear go to R-18 Island, where they discover to be the Eden's base of operations.
Characters are shown in order of appearance.