Squad 13 is a group of Parasites who are the main characters of the series. The squad consists of ten children who are about age 14, and are based out of Plantation 13, living within their home area, Mistilteinn, which is colloquially referred to as the ‘Birdcage’.
Squad 13 is unique most notably for their individually designed FRANXX but also because they refer to each other by names rather than their code names. Their names are based on Japanese readings of their code names.
After spending their entire childhoods in the Garden and undergoing training to become pilots, ten children are discharged and assigned to Plantation 13 based on their carapacity and aptitude results. They are paired up in boy-girl partners; the pairs are: Hiro and Naomi, Goro and Ichigo, Zorome and Miku, Futoshi and Kokoro, Mitsuru and Ikuno. They later participate in a graduation ceremony hosted by Papa, who praises them for their loyalty and dedication to protect the adults. Hiro is declined to be promoted as a stamen after he fails to synchronize with Naomi, resulting in both being ordered to return to the Garden. However, when a klaxosaur attacks the plantation during the squad’s startup trial, Zero Two abruptly fights it with Strelizia in stampede mode. Hiro is able to successfully synchronize with Zero Two and they quickly kill the klaxosaur. However, Zero Two was not allowed to formally join the squad because her partners always die after piloting three times with her, as her klaxosaur genetics cause her to subconsciously devour her partners. ever since his first flight with her, Hiro develops a large purple tumor on his chest as a result of her devouring him and he almost succumbs to the effects but his will power to prove his worthiness as a parasite enables him to overcome his illness and live past his third ride with her, vowing he will always be Zero Two‘s partner. As Hiro is the only stamen that is compatible with her and survived the third ride, she is officially enrolled into the squad and Hiro is declared as her official partner.
The other squad members were initially hesitant to accept Zero Two as a member due to her reputation but gradually come to consider a comrade due to having Strelizia as a necessity. Goro, Futoshi, Miku, Kokoro, and Ikuno find no reason not to accept Zero Two as she and Hiro have a positive influence over each other but Ichigo, Mitsuru, and Zorome are reluctant; this is due to Ichigo’s feelings for Hiro and her jealousy of Zero Two, Mitsuru is afraid of her after she seemingly tried to kill him when he piloted with her, and Zorome is still wary of her reputation. Due to the increasing klaxosaur attacks plummeting large amounts of magma energy, Plantations 13 and 26 are linked to transfer magma energies but are attacked by a horde of Conrad klaxosaurs and then a Gutenberg klaxosaur. Both squad initially struggle but Hiro and Zero Two help Two squad’s emerge victorious. Due to this victory, Squad 13 is awarded a trip to the beach, which is their first experience outside the plantation and they discover an abandoned modern city, leading them to wonder about previous human civilization. The squad later goes through a ‘gender conflict’ after the girls’ parasites suites melted in front of the boys during a battle, but after they learn there was a previous Squad 13 that was killed, everyone reconciles. Squad 13 is dispatched to stop a Gutenberg klaxosaur from colliding with the plantation but a disadvantage causes Goro to inject Ichigo from Delphinium and contemplate self-destruction to save everyone and the plantation. However, Ichigo reaches him in time to help him escape and he confesses his feelings to her, although he doesn’t expect a response due to her being in love with Hiro.
APE awards the squad for their significant victories and the children visit the city for the first time. Due to Mitsuru and Ikuno’s incompatibility, a ’partner shuffle’ is proposed; they may chose another partner they deem is more appropriate. Ikuno tries with Ichigo but the two fail to connect while Kokoro volunteers to partner with Mitsuru and they are able to connect, and become official partners while Ikuno pairs up with Futoshi. Zero Two’s relationship with the squad begins to deteriorate as she becomes more desperate to kill as many klaxosaurs as possible to “become human” and meet a boy from her childhood. Hiro is unable to control her and the squad begins to fear her when she nearly kills Hiro, whom she realizes is the same boy. Ichigo further alienates Zero Two by openly referring to her as a monster and begging Hiro to leave Zero Two for her. However, Hiro, remembering his past with Zero Two and acknowleding his love for her, refuses to give up in her and reaffirms his devotion to her, and they reconcile. The rest of the squad, wanting to see Hiro happy, also reconcile with Zero Two and truly welcome her into the squad. Hiro and Zero Two begin an official relationship and, unbek to the others besides Zero Two, Hiro begins developing klaxosaur characteristics, such as horns and fangs.
Unknown to them, they are left alone at their boarding house for a month as part of an experiment to test their emotional responses with each other. During this period, the children begin to enjoy their first sense of independence and discover concepts they were never taught; Ikuno reveals to Ichigo she is in love with her; Kokoro and Mitsuru start to fall in love and she reveals she knows about sexual intercourse and childbirth, admitting she wants to bear a child and they are all capable of bearing children. She and Mitsuru begin a romantic and sexual relationship, and decide to get married before the Squad is scheduled to report to a parasite camp. However, because this is prohibited, APE apprehends them and erases their memories. Finally realizing parasites are not allowed to live their own lives and will never become adults, Hiro confronts Papa and demands the squad be released from duty, which Papa agrees to do on the condition they win the battle at Grand Crevasse. The squad agrees to this and arrive at Grand Crevasse to battle a horde of klaxosaurs. Hiro and Zero Two are tasked with using Strelizia to control the ‘Star Entity’, a massive weapon within the facility, while everyone else serve as support. In midst of the battle, the klaxosaur princess manages to severely injure Zero Two and forcibly connect with Hiro to take control of Star Entity. A massive armada of spaceships appear and the klaxosaurs stop fighting. Papa then reveals he and some of his companions are members of VIRM and have been using mankind against the klaxosaurs. Although confused on who the real enemy is, Squad 13 decides to return to Grand Crevasse to help Zero Two rescue Hiro. After the two reconnect, due to the princess relenting to let the two stop VIRM and save the planet, they force VIRM to retreat but Zero Two is left catatonic.
Squad 13 is tasked with helping parasites recover from the confusion and trauma, and they begin attempting to grow crops to survive but learn magma drilling has left the soil deprived of natural resources. The children are also faced with the conflict of making their own decisions, especially when Kokoro finds out she is pregnant, and she and Mitsuru struggle to agree on whether or not to keep the child. Hiro deduces Zero Two is mentally fighting VIRM in space with Strelizia and decides to rescue her, although he is warned it will be a suicide mission. Goro especially advises him against it but Hiro’s resolves doesn’t waver because he says he can never forgive himself for leaving her behind. The squad, minus Kokoro and Mitsuru, then decide to accompany Hiro in his mission because they say the squad is not the same without Zero Two and they personally want revenge against VIRM. The surviving members of the 9’s accompany them as well and even sacrifice themselves to help Hiro reach Strelizia. At the same time, Kokoro and Mitsuru reconcile after he proves his resolve to stay with her and their child no matter what. After Hiro and Zero Two reconnect, they emerge victorious against the VIRM but large armada of it escape. Atmed with a klaxosaur bomb, they then travel through a warp gate to find and destroy the surviving VIRM while the rest of the squad returns to Earth to begin rebuilding society and the planet.
Over the next two years, many events unfold for the parasites; Kokoro gives birth to her and Mitsuru’s daughter Ai, Naomi is rescued along with other missing children, and the parasites begin harvesting crops from fresh soil from the plantations. Hiro and Zero Two eliminate numerous armadas of VIRM before reaching the VIRM home planet. They are almost defeated until Squad 13 senses something is wrong due to Ai’s intuition and begin sending their prayers to the two. Hiro and Zero Two hear their thoughts and reconnect, and plant the bomb into the planet. To safeguard the lives and future of their friends, Hiro and Zero Two sacrifice themselves and detonate the bomb while vowing they will meet again on Earth as long as their souls exist. Everyone later mourns their deaths.
During the next eight years, the parasites develop a self-sufficient lifestyle and allow the world to prosper. Ikuno works hard to develop a cure for the accelerated aging process of the parasites and she succeeds, although this leaves her sickly and bedridden. During a school entrance ceremony, the squad reunites and are shown to be living happily; Goro, who is a traveler, and Ichigo are married and expecting their first child, Kokoro and Mitsuru are still happily married and have four children, Miku and Zorome are teachers for the next generation, Futoshi is a baker and married with three children, and Ikuno is a doctor and in a relationship with Naomi. The squad gathers at a cherry blossom tree to remember Hiro and Zero Two, thanking them for the lessons they learned from the two and their sacrifice to give them the freedom to live good lives.
A thousand years pass, when Hiro and Zero Two’s souls return to Earth and are reincarnated into two children who meet at the cherry blossom tree.
Hiro - The male protagonist. He is considered a prodigy but struggles to find his purpose in life after failing to pilot until he partnered with Zero Two. He has known Zero Two since childhood and is deeply in love with her. He is the one responsible for giving all the parasites names and is determined to free them from APE’s control. He dies after sacrificing himself to save his friends and the planet from VIRM and is later reincarnated.
Zero Two - The female protagonist. She is a klaxosaur-human hybrid as a result of Dr. Franxx’s experiments. She has a dark past due to her partners dying shortly after piloting with her, with Hiro being the only exemption. She has a rocky relationship with the squad at first but gradually is accepted. She is deeply in love with Hiro and is determined to stay with him forever. She sacrifices herself with him to stop the VIRM and they are later reincarnated.
Ichigo - The leader of the squad. She is Goro’s partner. Hot-tempered and matter-of-fact, she is not well-liked by her squadmates and she demands they always follow her orders no matter what. She had known Hiro and Goro since childhood, and is in love with Hiro, and is jealous of Zero Two. However, she later accepts the pair and ends up with Goro, with whom she marries and has a child.
Goro - A childhood friend of Hiro and Ichigo. He is Ichigo’s partner. He tends to be optimistic and friendly due to wanting to avoid conflict. He is in love with Ichigo but doesn’t pursue his feelings due to her feelings for Hiro. He eventually confesses to her and she later reciprocates. They later get married and have a child.
Zorome - He is Miku’s partner. He is an immature, loud, and arrogant parasite who often argues with the others but he truly cares about them and will defend them. He seems to be closer to Miku, although they fight constantly, as he refuses to renounce their partnership. He dreams of becoming an adult. He later becomes a teacher.
Miku - She is Zorome’s partner. She has been best friends with Kokoro since childhood. She is stubborn and tends to speak her mind. Although she quarrelse with Zorome, she cares deeply for him and considers him as her only partner. She later becomes a teacher.
Mitsuru - He was Ikuno’s partner and later became Kokoro’s partner. He has known Hiro since childhood and used to hold a grudge against him for supposedly breaking a promise but they reconcile after he learns it wasn’t Hiro’s fault. He falls in love with Kokoro and they get married. Even after their memories are erased, they remained together and have four children.
Kokoro - She used to be Futoshi’s partner and later became Mitsuru‘s partner. She had been best friends with Miku since childhood and she is deeply in love with Mitsuru. She pursues him by becoming his partner and admitting her desire to have a child. They get married and conceive their first child before their memories are erased. Despite this, they remained together and have four children.
Futoshi - He used to be Kokoro‘s partner and later became Ikuno’s partner. He is an overweight parasite who eats all the time and is good friends with Zorome. He is infatuated with Kokoro and jealous of Mitsuru but he later accepts them as a pair. He later becomes a baker and marries with three children.
Ikuno - She used to be Mitsuru’s partner and later becomes Futoshi’s partner. She hates the boy-girl pairing system due to that she is in love with Ichigo and struggles to express her true feelings. She develops a cure for accelerated aging process of the parasites but this leaves her sickly and shortens her own lifespan. She later enters in a relationship with Naomi.
Naomi - Hiro’s original partner before Zero Two. She left The squad after failing to pilot with Hiro and disappeared afterward. She is later revealed to be alive and rejoins her former team, and begins a relationship with Ikuno.