Zenshu episode 4: Memmeln is revealed as the traitor as Natsuko and Luke stop the ultimate calamity

Zenshu episode 4, titled Eternity, premiered in Japan on Sunday, January 26, 2025, at 11:45 pm JST. This episode featured one of the series' most shocking developments yet, as Memmeln was revealed to be a traitor working to bring about the end of the world.

The stakes in this episode were much higher than the previous ones. In this episode, Natsuko Hirose not only solved a major mystery of the original story of A Tale of Perishing, but she also managed to save the day by preventing one of the series' most heartbreaking tragedies with the help of her animator powers.

Zenshu episode 4: Natsuko discovers Memmeln's betrayal and stops the summoning of the Ultimate Void

Zenshu episode 4 opening moments

Luke and Natsuko in the opening moments of Zenshu episode 4 (Image via MAPPA)

Zenshu episode 4 began with Luke Braveheart and Unio discussing the possibility of a traitor being among them. They arrived at this conclusion after revisiting the Void monster's invasion in the previous episode, the circumstances of which could have only been brought about by a magic user.

Natsuko Hirose, on the other hand, knew that the said traitor was none other than Luke's trusted friend and fellow member of the Nine Soldiers, Memmeln.

Apparently, in the original story of A Tale of Perishing, Memmeln tried to kill Luke while being disguised as the Ultimate Void, only to die at his hands. Given that the reason behind Memmeln's betrayal was never explained in the movie, Natsuko decided to find out the truth on her own by following Memmeln.

Zenshu episode 4: Natsuko and Luke discover Memmeln's betrayal

Memmeln as seen in the anime (Image via MAPPA)

While Natsuko was initially successful in shadowing Memmeln's movements, she was eventually caught in the act by Luke. Natsuko explained to him that Memmeln was the traitor who let the Void monster into the Last Town. Although he was caught off-guard by this revelation, he decided to accompany Natsuko in her mission of following Memmeln.

The two eventually arrived at an isolated cemetery, where Memmeln's choir apparently held practice. There, they discovered a secret entrance to a cave, where the choir could be heard practicing. However, upon closer inspection, Natsuko and Luke witnessed the horrifying truth with their own eyes— Memmeln and her choir members were seemingly a cult that was devoted to summoning the Ultimate Void.

What's more, Memmeln was apparently the leader of the said cult. After witnessing all this, Luke tried to intervene and confront his team member on the spot. Fortunately, Natsuko stopped him from blowing their cover. She explained that they needed to come up with a plan to confront Memmeln. As such, they retreated from the scene.

To complicate matters further, Unio appeared at the scene to visit Memmeln's choir practice. Thankfully, Luke and Natsuko managed to convince him otherwise by dragging him off to get milk beers.

Zenshu episode 4: Natsuko and Luke confront Memmeln

Natsuko Hirose as seen in episode 4 (Image via MAPPA)

After spending some time planning their next move, Natsuko directly confronted Memmeln about her involvement in summoning the Ultimate Void. Memmeln, realizing that she can no longer hide her darkest secret, confessed everything.

She explained that elves usually have a prolonged lifespan, due to which they live a long life full of pain and suffering. After losing her friends over and over, Memmeln realized she could no longer continue living her life and wanted everything to end.

One day, Memmeln came across a group of people who wanted to end their suffering as well, by summoning the Ultimate Void, which would bring an end to their world. Since then, they had been working tirelessly to accomplish their mission of bringing forth the great calamity. After her confession, Memmeln claimed that she would leave her punishment up to Luke and his team. However, Luke was moved to tears after hearing about Memmeln's tragic life.

Zenshu episode 4: Natsuko's creation saves the day once again

Memmeln and the Ultimate Exister in episode 4 (Image via MAPPA)

Shortly after Memmeln's confession, Luke and Natsuko managed to formulate a plan to save Memmeln and stop the Ultimate Void from coming to life. However, once they enacted their strategy, things quickly went south when Natsuko realized that Memmeln was fast-tracking her plan of summoning the Ultimate Void by performing the final ritual.

Worried that Luke might end up killing Memmeln to stop her, Natsuko made a last-ditch attempt at saving her team member by using her animator powers once again. This time, she recreated a beloved idol figure from the first anime she had worked on. The idol, named Ultimate Exister, was created to bring about a change in the hearts of Memmeln and her cult members.

Fortunately, Natsuko's creation was successful in purifying the hearts of Memmeln and her group by giving them a renewed purpose of living. However, immediately after the Ultimate Exister disappeared, Natsuko ended up collapsing due to the toll her powers took on her body.

Zenshu episode 4 closing moments

Natsuko and Luke as seen in episode 4 (Image via MAPPA)

In the closing moments of Zenshu episode 4, Memmeln was seen sporting a more upbeat and relaxed attitude. This was because she, along with her cult members, had become obsessively infatuated with the Ultimate Exister and wanted to be his fans for all eternity.

While Memmeln thanked Natsuko for giving her a new purpose in life, Luke and Unio were seen outside working in the garden. Upon learning the truth behind everything that had happened so far, Unio expressed his relief, since he had assumed that Natsuko and Luke were dating in secret and were thus acting suspicious.

This caused Luke to become excessively flustered, prompting Unio to get even more suspicious of them. With this, the climactic episode came to an end.