The episode opens with a flashback to fifteen years ago, as a number of refugees are seen applying skin patches to determine Oracle Cell compatibility. Those whose patches return a positive result are directed to go inside and register; those who are negative, a vast majority, are held outside. The Utsugi family, among those who could not enter, notice a crying newborn Lenka nearby at the direction of their daughter, Iroha. However, immediately thereafter, Ogretails attack and massacre large swaths of people, as the father of the family picks up Lenka and runs with his wife and daughter. Later, as the family hides in an abandon church, the father resolves to keep the baby, with Iroha picking a name.
Meanwhile, back in the present, Lenka undergoes a compatibility test for his restored God Arc. Despite warnings of increased pain, he still decides to go through with it.
Back in the past, Lenka, now a young boy, is keeping watch for his family as his father comes out to switch places. It is revealed that Lenka and his family are now part of a small community of survivors, making their home in an abandoned warehouse. However, a number of them are sick—a count that includes Lenka and Iroha’s mother. As Lenka gives his duty rations for lookout to his mother, she begins coughing up copious amounts of blood. Meanwhile, Lenka’s father announces that the survivors will have to use what little fuel they have left to search for a medicine. Iroha tells her mother that she and Lenka will be in a different group from their father, to which her mother responds by giving Iroha a folded shoulder cape from a uniform.
On a truck, Lenka swings around a large bone and tells Iroha that he’ll kill any Aragami they find, subsequently expressing his possible doubts about the success of the mission and whether the medicine will help. Later on, the group finds some medicine, but they are immediately set upon by a crowd of Ogretails, with only Lenka and Iroha making it out alive. The survivor’s guilt overtakes Lenka as the two of them make it to a river, Iroha washing Lenka’s foot in the water as he wonders if they, too, will be eaten eventually. They discuss their dreams for the future, Iroha announcing that she wants to bring plant life back to the world and Lenka stating his desire to become strong enough to protect everyone.
However, immediately thereafter, the two are found by the Ogretails from earlier, Iroha brandishing a knife to defend herself as Lenka unsheathes his bone and gets in front of Iroha to protect her. As the bone breaks futilely against the Ogretail’s head and Lenka is about to be eaten, a young Lindow Amamiya suddenly arrives on the scene and vanquishes the Aragami, announcing himself as a God Eater.
He accompanies them back to the camp but is met with hostility from those who took the test eight years prior and failed. Lindow inquires as to whether Iroha and Lenka took the test as well, stating that Fenrir is looking for candidates and that those who test positive can become God Eaters, with family members of positive candidates permitted to come along. The father expresses his gratitude to Lindow, but states his disapproval of how Fenrir operates. Lindow takes his leave, but leaves them with a package of test patches. However, as Lindow is about to depart, Lenka approaches him and asks if, by becoming a God Eater, he can become strong enough to destroy Aragami. Lindow asks him what he thinks strength is for, whereupon Lenka responds without hesitation that it is used to protect people. Iroha subsequently arrives on the scene, trips into Lindow’s arms, and introduces herself and her brother to Lindow, as Lindow returns the favor and passes on the compass seen in Lenka’s possession in previous episodes. However, as Lindow leaves, Lenka begins showing signs of the same illness afflicting their mother and the other survivors.
It is then revealed that the Utsugis only have enough medicine to administer to one person, being forced to choose between saving the mother or Lenka. The mother immediately requests the medicine be given to Lenka, as well as the compatibility test administered to him. As they peel off the patch, the color of the skin is orange—a positive result. With that, their mother cements her desire for Lenka to receive the medicine, but Iroha and the father are paralyzed with sorrow. However, the mother states that Lenka might one day be able to bring about a future that can overturn this world’s own future of despair. Lenka is subsequently administered the medicine, with the mother requesting Iroha take good care of him before she passes away. The rest of the family bury her in a makeshift graveyard, as Lenka reaffirms his desire to become strong.
Years later, Lenka returns to a camp where Iroha resides, having been “out” on an expedition. However, as Lenka removes his backpack, he reveals a large gash in his arm, which Iroha later bandages up, revealing Lenka’s back as bearing two immense scars already. As Lenka prepares to go to a meeting, Iroha gives him the shoulder cape that their mother gave to her years ago. Shortly thereafter, one of the survivors announces the near-complete depletion of their resources, as well as a complete lack of fuel.
Iroha is then seen finding their father, announcing that she can’t find Lenka anywhere. Their father announces that tomorrow is Lenka’s fifteenth birthday, stating that this might be the right time to send him to Fenrir. Iroha, however, is against it, stating that she doesn’t want their family to be split up, before the sound of a large explosion disrupts the two of them.
Lenka is seen on another expedition discovering a fuel canister with some fuel still remaining; however, he is immediately assaulted and wounded by a lone Ogretail before he escapes, the Ogretail in close pursuit. Suddenly, he steps on loose ground and causes a cave-in, the ground collapsing below him and dropping him underground. As the Ogretail walks away, Lenka gets up and picks up the fuel canister, taking it with him back to camp—only to find the camp under attack by Aragami, his sister seemingly the only survivor and the status of their father unknown. As the two of them depart, they find their father crushed under enormous rubble, and an Ogretail closes in on their position as Lenka attempts to free his father. Iroha joins in the effort; however, more Ogretails appear, the father demanding that the two of them leave without him, telling them to take a motorbike he hid just in case. Lenka still attempts to free his father; however, a slap from Iroha brings him to his senses, and the two of them flee the scene as the Ogretails mercilessly devour their father.
The two of them get on the bike and ride away, but a pursuing Kongou slashes Iroha’s leg as she tells him to head south. Lenka is later seen bandaging Iroha’s leg, as the two of them travel across various landscapes heading towards their destination. However, the wound becomes too much to bear, and Iroha collapses as Lenka removes the bandages to find that her leg has become necrotic. Iroha hands Lenka Lindow’s compass and tells him to go to Fenrir, saying that they—Iroha and her parents—couldn’t have gone with him, as they were not related to him by blood. As multiple Ogretails close in on them and Lenka refuses to leave Iroha’s side, she draws her knife and without hesitation slashes her own throat, stating that Lenka wouldn’t have left her side otherwise.
As Iroha explains Lenka’s origins and the origins of his name, she resolutely tells him to go forth and overturn this world without a God to pray to. He departs, his resolve reaffirmed, and the Ogretails overtake her as she awakens in a world filled with greenery, noticing a lone lotus flower—Lenka’s namesake—blooming in a river, Lenka himself standing on the opposite bank. Iroha runs over to him and embraces him, saying “I love you” one last time as she is subsequently seen being devoured by Ogretails, tears flowing down her lifeless face.With a mighty yell of resolve, Lenka runs across the desolate landscape, as the scene shifts back to the beginning of the episode, with Lenka undergoing the compatibility test for his new God Arc. Johannes tells him to reaffirm his purpose, which Lenka states (“To kill Aragami!”) as memories of his time at Fenrir—and Iroha’s last words—come rushing back, Lenka staring forward resolutely with a desire to fulfill his sister’s final wish.