MitsuKoko

MitsuKoko is the het ship between Mitsuru and Kokoro from the DARLING in the FRANXX fandom.

Canon
Mitsuru and Kokoro knew each other since their childhood days in the Garden, but they barely knew each other and didn’t interact much. At the age of 14, they were assigned to the same FRANXX squad. Still, they barely interacted with each other as they had little need to and shared no common interests. Mitsuru is a lone wolf who has little to no need for his comrades and is not afraid to speak his opinion. On the other hand, Kokoro is a shy, quiet girl who is afraid to say what she really feels, usually going with the flow to get along with her comrades. After Mitsuru is traumatized by piloting with Zero Two, Kokoro starts showing concern for Mitsuru's well being. She finds him sulking in the greenhouse she offers to listen to his problems. Kokoro comments she found Mitsuru's independence admirable, although Mitsuru misinterprets it as pity and coldly tells her to leave him alone as he walks away. When Squad 13 is rewarded with a short getaway at the beach, Mitsuru finds the remains of an abandoned city and tells his squadmates, hoping to do some exploration. Kokoro voices her fears of the cavern, to which Mitsuru replies she didn't need to come if she was afraid. He explains this is because he couldn't guarantee anyone's safety. However, Mitsuru manages to save Kokoro from getting crushed by a falling bookcase in an old clinic later, implying he has been following her closely. He also notices Kokoro had picked up a book about childbirth and reproduction - banned information but chooses not to mention it.

During the Boys x Girls fight, Kokoro and Mitsuru bump into each other at the greenhouse. Mitsuru explains he was at the greenhouse as it was a good hiding place. Kokoro chats about the 'language of flowers'. When she realizes Mitsuru doesn't seem to be listening, she asks if she is bothering him because of the fight, to which he replies he finds the fight stupid and can't be bothered about it. Kokoro praises him for his bravery, stating it took a lot of courage to be honest. As Mitsuru walks to leave the greenhouse, Kokoro accidentally drops the book with banned information she found at the abandoned town. When Kokoro admits she had kept the book, Mitsuru stated the book didn't involve him and implied he'd keep it a secret. While not stated, it is implied that Mitsuru's bravery of being honest might have given Kokoro the courage to speak up to her fellow pistils to end the fight later on. Ichigo and Ikuno notice this, even commenting on how unusual it is for Kokoro to be so assertive.

Whilst on a special mission to defend the S-Planning facility, Mitsuru collapses due to 'child fever' and puts Chlorophytum out of commission. Kokoro becomes concerned for Mitsuru upon learning he had a risky injection to become a parasite when he was a child. Even after recovering, testing finds he and Ikuno's sync rate has dropped so low Hachi notes he could become a pruning target. This leads to Nana suggesting the option of a partner shuffle between the members of the squad. Despite promising to be partners with Futoshi forever, Kokoro is uncomfortable with his feelings for her because she doesn’t feel the same. Kokoro volunteers to try riding with Mitsuru, shocking the entire squad, including Mitsuru, and bringing Futoshi to tears. Kokoro and Mitsuru try testing their para capacity and although it is in the lower range, it is stable. However, Mitsuru is indifferent to the arrangement.

Later on, he finds Kokoro talking to herself and playing with her baby doll in the greenhouse. She jumps when he asks her what she is doing, then they start chatting. Kokoro asks why he thinks humans stopped having children because having a baby was the most natural thing in the past. Mitsuru doesn't care to know why and tells her not to think of unnecessary things. He asks her if she became his partner out of pity but she denies this. On their first mission as a pair, their connection falters due to Mitsuru blindly crashing Genista head-on after failing to eliminate klaxosaurs. The klaxosaur is about to crush them with its foot when Chlorophytum runs in order to protect them, saving them.

Inside Genista, Kokoro asks him to reconnect, but Mitsuru tells her he's incompetent and shouldn't get her hopes up. Kokoro refutes his claim, telling Mitsuru to lean on and trust her more, to which Mitsuru reveals the childhood promise he and Hiro made to pilot together but Hiro broke. He reveals that incident shattered his faith and he can’t bring himself to trust in anyone, fearing his trust will be broken again. Kokoro comforts him, saying she also broke a promise and hurt Futoshi, and she isn't the sweet girl everyone thinks she is. She adds that they aren’t perfect and these things are bound to happen. Hence they shouldn't dwell in the past. Mitsuru asks Kokoro if she means he should forgive Hiro and she says only he can make that decision but she wants to laugh and have relationships with everyone.

Kokoro reaffirms that she believes in him and attempts to operate Genista in stampede mode. Even though Kokoro is getting hurt during the stampede she doesn't stop, even after her squadmate tells her to, wanting to prove Mitsuru's competency. Luckily, Mitsuru intervenes and pulls her off the machine before she can get seriously hurt. As MitsuKoko lay on the floor, Mitsuru looks up at Kokoro and asks how she can trust someone to the point of hurting herself, to which Kokoro smiles sheepishly. Mitsuru smiles back at her, commenting he finds her ‘unbelievable’. MitsuKoko reconnects and their para capacity levels shoot to the maximum. Genista is reactivated and blasts a bigger hole in the klaxosaur to reveal its core. Strelitzia leaps in to land the finishing blow and eliminates the klaxosaur.

Upon returning to the FRANXX hanger, Futoshi berates Mitsuru for his recklessness. Kokoro attempts to intervene but Mitsuru stops her. Futoshi punches him and Kokoro goes to comfort him. Following Futoshi's yelling, Mitsuru promises to protect Kokoro as long as they are together, shocking both Kokoko and Futoshi. Although he makes it sound like he is just saying it to pacify Futoshi, it is implied he really means it.

After this incident, MitsuKoko grew closer. Often seen positioned next to or near each other in most scenes, MitsuKoko back up each other's statements and encourage each other during battle. Most notably, they learned from each other, as observed as Kokoro learning to speak her mind bravely and Mitsuru opening up to and trusting his squad mates.

After the first battle of the Gran Crevasse, Squad 13 was on standby at Mistilteinn, awaiting further orders. By this time, MitsuKoko has grown much closer to each other and their conversations are much deeper and serious. In fact, they are so close that Mitsuru requests a haircut from Kokoro, something which is seen as intimate in Japan. Mitsuru admits his guilt for how badly he treated Hiro for something that wasn’t Hiro’s fault and, without this grudge, he feels he no longer has a drive to keep him going. When Kokoro finishes, she smiles and laughs, and he asks if his hair looks weird, and she says he looks handsome. When Kokoro gets up and compliments him for reconciling the misunderstanding with Hiro, Mitsuru compliments her handiwork and says she's very kind. Kokoro is taken aback by Mitsuru's words and seems flustered. Dropping to her knees, she kisses Mitsuru. Mitsuru is surprised, but he doesn’t push her away. Kokoro realizes what she did and gets embarrassed, apologizing as she ran off.

Later when the girls are bathing at the lake, Miku laughingly asks if they had seen Mitsuru's hair. Kokoro is surprised and Miku smirks at her, asking Kokoro if she cut it. Kokoro giggles awkwardly as she'd cut it herself, to which Ikuno commented she thought it looked good on him. In the evening, Miku wonders what would happen to them if their food rations stopped being dropped off weekly. Zero Two announces the only choice they'd have then would be to make their own food together. At first, Zorome seems skeptical about whether they can pull it off, but Hiro agrees to Zero Two's suggestion. Mitsuru adds that he remembers seeing some cookbooks in the library, to which Kokoro exclaims perhaps they could do it after all. Everyone happily agrees to Zero Two's suggestion, except Zorome. Kokoro uses her knowledge of plants to make a salad out of edible plant parts while Mitsuru makes a salad dressing using their food rations. When Squad 13 sits down for dinner, Miku tastes their salad and says it's good. Kokoro cheers and smiles at Mitsuru, glad their joint effort worked out. After the 9's arrived at Mistilteinn, MitsuKoko is seen in the greenhouse again, Kokoro brushing Mitsuru's hair and chatting. Mitsuru says he'll be a bit sad to leave since they only began spending time together after they were left to fend for themselves. Kokoro smiles and pats his hair before touching the base of his neck, which confuses him. Kokoro explains she read that boys and girls can create new life by joining their bodies together and curiously touches his chest, making a sexual proposition to him. Gulping, Kokoro unzips Mitsuru's uniform, saying she believes procreation represents hope for them. Mitsuru feels extremely uneasy at this point, so he shoves her hand away, standing up and asking what she's doing. After Zorome walks in on them to remind Mitsuru about water duty, Mitsuru sends Zorome away and asks Kokoro where'd that came from and was shocked to hear Kokoro had been thinking about it for a long time.

Mitsuru later meets Hiro while on water duty. After a chat, Hiro helps Mitsuru realize he is in love with Kokoro. This puts his mind at ease on his feelings and makes him even more determined to support and make Kokoro happy.

Upon returning to the boarding house, Mitsuru and Hiro found the rest of the squad gathered in the living room because Zorome told them what he saw. The 9's come in and berate Kokoro for keeping the baby book. Kokoro confesses to her squadmates that she wants to have a child so she could 'leave her mark on the future'. Since Kokoro hadn't directly told him about this, Mitsuru is shocked and confused. Upon hearing Kokoro's intentions, Nine Alpha calls Kokoro disgusting for trying to defy Papa, their avowed leader. Mitsuru tries to stand up for Kokoro, but not before Ikuno attacks Nine Alpha. This requires their caretakers to intervene and break up the fight while interviewing Kokoro about rebelling against Papa. Later that night, Mitsuru waits for Kokoro in the greenhouse but she doesn’t show up. He then finds Kokoro crying in one of the sealed off rooms. Kokoro tries to apologize for trying to force Mitsuru into it and he says she wasn’t but she calls him a liar. She tells Mitsuru to leave her alone, but Mitsuru doesn't want to hear any of that. As Kokoro gets up to leave, Mitsuru says he won’t leave her alone and pulls her into a hug, telling her to lean on him more. He tells her not to decide things on her own and expresses his desire to make her happy. As Kokoro cries, she wonders if creating new life is really such a bad thing and if they are allowed to think of their future. Mitsuru chokes back his tears and kisses Kokoro, who pulls him closer. After consummating their relationship, MitsuKoko is later shown lying naked in each other's arms. Following this, they start meeting in the abandoned room in secret to spend their nights together.

Before Squad 13 leaves Mistilteinn for the Bird Nest, they decide to hold a wedding for MitsuKoko as suggested by Hiro. After learning what marriage means, MitsuKoko like it and decide to get married themselves. On the day of the wedding, Mitsuru shyly looks at Kokoro in her wedding gown. Kokoro links arms with Mitsuru and tells him to find happiness together. As they walk down the aisle arm in arm, their squadmates throw sakura petals and ring bells to welcome them. Mitsuru and Kokoro exchange the rings Mitsuru made earlier and proceed to seal their wedding vows with a kiss. However, the 9’s and an APE assault team crashes the wedding and to take MitsuKoko away for indoctrination. Squad 13 tries to fight back but are outnumbered by APE's soldiers and the 9's. Kokoro cries out for Mitsuru and he tries to save her before he is knocked out and they are taken away.

Squad 13 are sent to the Bird Nest and wait weeks for MitsuKoko's return. When Mitsuru and Kokoro do return, the squad's worst fears come true. They realize all of MitsuKoko's memories of each other have been removed. MitsuKoko not only do not remember their relationship prior to the mindwipe, but they also don't even recognize each other and are confused when their squadmates tell them they were FRANXX partners previously because they think the other is a new team member. Kokoro attempts to partner with Futoshi again but he refuses and insists that she stay with Mitsuru. They then talk about how their friends keep telling them about what happened to them but both don’t remember. Mitsuru says he doesn’t think he will develop feelings for her and she agrees. They are later seen talking to each other, supposedly getting to know each other better. After settling down at the Bird Nest, MitsuKoko take off their wedding rings, puzzling Futoshi. Kokoro gets nauseous from morning sickness and runs to the bathroom to throw up. Ikuno mentions it has been happening a lot lately and Ichigo suggests Kokoro take time off the upcoming mission. Kokoro states Papa sent her back even after erasing her memories, so she must fight to death for him. Miku is shocked and exclaims that none of them belonged to Papa because Kokoro and Mitsuru showed them that they all must leave their mark for the future. However, Kokoro doesn't remember the wedding and is perplexed.

MitsuKoko stands in front of Genista in the FRANXX hangar. Mitsuru enters Genista and reassures Kokoro they will be able to connect since their squad mates state they were FRANXX partners before. Kokoro does not say anything and rubs the base of her finger where she used to wear her wedding ring.

During the 2nd battle of the Gran Crevasse, Mitsuru compliments Kokoro for fighting well and calls her by her nickname. By doing so, he recalls his erased memories and triggers a painful flash. The pain and the shock catch him off guard, causing him to disconnect from Kokoro. As Genista struggles to regain control, Kokoro asks Mitsuru what is happening. She calls him by his nickname and gets the same painful flash too. MitsuKoko surmises the pain is caused by saying each other's names. Bewildered and terrified, they shut down their FRNAXX, forcing Delphinium to support Genista. While Genista does not continue in the fight afterwards, it is part of the mission to bring Zero Two to Hiro. Kokoro expresses her desire to keep fighting even if she dies, which concerns Mitsuru. He tells her they need to work with their friends as a team to survive the battle against VIRM rather than going into the fight and readying themselves to die. Although she seems reluctant to listen, she agrees. Following the battle against VIRM, the parasites are left to fend for themselves with low food supplies and the lack of maintenance. At a meeting, Kokoro seems to keep her distance from Mitsuru, who keeps looking at her with concern. Kokoro then becomes nauseous due to morning sickness and excuses herself. Mitsuru gets up to check on her out of concern but stops himself and the meeting resumes.

The next day, the parasites are working in the fields again when they discover the remains of a klaxosaur and a VIRM soldier which killed each other. Kokoro collapses due to nausea and Miku rushes to her aid. As Kokoro drifts in and out of consciousness, Mitsuru reaches out to Kokoro and calls out her name despite the searing pain in his head.

When Kokoro comes to, she is in a hospital ward surrounded by her squad mates. The new Nana says her urine sample revealed traces of HCG, which confuses Kokoro. The new Nana explains Kokoro is pregnant and cannot pilot a FRANXX anymore. Upon hearing this, Mitsuru realizes he fathered the unborn child and falls to the ground in shock. Kokoro reacts in a similar manner, grasping her sheets tightly. The new Nana recommends abortion as a treatment and asks Kokoro to let her know when she makes a decision on whether to abort or give birth. As the new Nana leaves, Kokoro calls for help out of fear and confusion as she is in a dilemma on what to do next. Mitsuru sits on the floor, shell-shocked, as Miku asks the boys to leave the room.

As the boys walk down the hallway, Mitsuru, guilt-stricken for causing Kokoro pain and unsure which choice is right, stops and asks Hiro what to do, but Hiro can't answer him. Following this, Mitsuru goes to Kokoro's room in an attempt to talk things out but is too afraid to face her. Later that night, as the squad reflects whether they will find something they will die for, Mitsuru realizes the importance of being a parent and decides he wants Kokoro to keep their baby. The next morning, Squad 13 leaves for space to help Hiro rescue Zero Two, but Mitsuru and Kokoro stay behind. As Kokoro still hasn’t made a decision on what to do with the baby, she does not join the squad in this mission as she is no longer able to pilot a FRANXX. Mitsuru chooses not to go because, as he tells Hiro, he wants to reconcile with Kokoro, who is surprised.

When Kokoro asks him why he didn’t go with another partner, Mitsuru explains he feels it is his responsibility to take care of Kokoro and their child, to which Kokoro coldly replies he didn't have to. Since they didn't even remember past memories of each other, she says she already told him that she didn't expect anything from him, implying that he had told her his decision to be there for her and the baby earlier but she rejected him. It is worth noting that at this point, Mitsuru and Kokoro seem to have 'swapped roles' in their relationship. Prior to the Partner Shuffle, Kokoro would reach out to Mitsuru and try to comfort and support him in the period when he was struggling to pilot, but Mitsuru would coldly reject her. Now, Mitsuru is trying to reach out to Kokoro in attempt to show support and concern during the time she struggles with the choice of abortion or keeping their baby, but Kokoro rejects his help. More wounds appear on Zero Two's body and Kokoro struggles to keep up with them. The battle in space intensifies and causes a giant thunderstorm on Earth. Despite this, Kokoro still stays by Zero Two's side despite the ill effects the rain might cause to her body. Mitsuru runs to Kokoro's side and tells her to get inside or she might fall ill and it will be bad for the baby. Kokoro doesn't listen and says she doesn’t care because, since she can‘t pilot anymore, she was pretty much useless and had nothing to live for but she wants to make herself useful by using her body to protect Zero Two. Mitsuru decides to stay with them and she pleads for him to leave her alone and she doesn’t hold him responsible for the baby but he replies he is not trying to be responsible and tells Kokoro if she has nothing, he doesn’t too. He adds, however, he's found his reason to live - to protect Kokoro and their baby's future. Mitsuru takes out his wedding ring from his right pocket as proof of his willingness to commit himself to her. The pocket Mitsuru took his ring from was the same one he touched after failing to talk to Kokoro after her hospitalization, implying he'd tried to do the same thing then but did not have the courage to.

Kokoro asks why Mitsuru still had his wedding ring and why he would still say her name even though it hurt him. Mitsuru replies even though he feels he's a weakling and doesn't really know what 'love' means, he feels that if they're together they'll be able to keep walking through any challenge and they can start over. He adds that this is their battle and he'll call her name as many times as she wants. Kokoro cries as they interlock hands and cry out each other's names as they embrace. When the storm passes, MitsuKoko watches Zero Two walk towards the sky and her body turn into a statue. They are later seen holding hands behind the statue, wearing their wedding rings. It is worth noting that, although both initially were ready to move on with their lives by removing their wedding rings and agreeing they would never develop feelings for each other again, they kept the rings likely because they still felt a connection to each other and it felt wrong to get rid of the rings. This implies deep down, both were waiting for each other to reach out and didn’t want to truly forget their past.



Afterwards, Kokoro begins to warm up to Mitsuru and Mitsuru becomes more protective of Kokoro, to a point where Kokoro has to tell him not to worry so much. As Kokoro's pregnancy progresses, Mitsuru is glad when Kokoro receives the treatment needed for her pregnancy, and he finds excuses to spend time by Kokoro's side and at times has to be dragged back to the fields by Zorome and Futoshi. 245 days after Hiro and Zero Two entered the warp gate, Mitsuru rushes to Kokoro's hospital room. Upon reaching, he sees that Kokoro has given birth to a baby girl. Mitsuru is overcome with love for his daughter when he sees her for the first time. Kokoro refers to Mitsuru as 'papa' and tells their daughter he's here. When their daughter reaches out and holds his finger, Mitsuru is overwhelmed with joy and cries. After leaving the room, Futoshi congratulates Mitsuru for being the first parasite to become a father. Over the next two years, MitsuKoko happily raises their daughter together and this allows them to gradually grow closer to each other.

Two years after HiroZero entered the warp gate, MitsuKoko's daughter, Ai, helps MitsuKoko realise Zero Two's statue is somehow linked to Zero Two in space. MitsuKoko calls the rest of the parasites up, joining hands with each other to send their thoughts and prayers to HiroZero. They tell HiroZero about Ai and the meaning of her name as they proudly look at their daughter and each other, showing they have grown to love each other again. After HiroZero's sacrifice, Kokoro drops to the ground, crying as she was touched by the sacrifice made. Ai comforts her and Mitsuru kneels down to her side to comfort her too. Sometime later, Kokoro gives birth to their second child which is a boy.

Eight years after HiroZero's sacrifice, the parasites have a reunion at a school ceremony. MitsuKoko is shown to have three children, with a fourth on the way. As Zorome and Miku argue, MitsuKoko giggles. After the school ceremony, they stand next to each other with the rest of Squad 13, recalling the lessons HiroZero taught them.

Quotes
"Kokoro! Please don't run off alone. I told you, didn't I? I can't guarantee your safety."

- Mitsuru, to Kokoro after saving her from falling debris

"Mitsuru, you can rely on others more, you know. I'll believe in you, so believe in me too."

- Kokoro, following the Partner Shuffle

"I promise... I promise to protect Kokoro from now on."

- Mitsuru, to Futoshi following the Partner Shuffle

"It's funny. Hearing that from you makes me feel like I can do anything."

- Mitsuru, to Kokoro after Kokoro gives him a haircut

"That’s it. I... love Kokoro?"

- Mitsuru, after talking with Hiro about his feelings for Kokoro

"Let's find happiness together."

- Kokoro, to Mitsuru on their wedding day

"Please don't say you have nothing. If you don't have anything, neither do I! But I've found my reason to live. I want to protect you and that baby's future. I'm a weakling! And I don't really understand what love is, either. But I can keep walking if I'm with you. That's what I've come to believe."

- Mitsuru, to Kokoro during the thunderstorm

Children
Series' finale shows Mitsuru and Kokoro have three children plus one on the way. Only one of them has their revealed name for now:

Ai Ai is the firstborn daughter of Mitsuru and Kokoro. She is also the first naturally born child to the Parasites after APE's departure. Ai is the Japanese word for "love" (愛). Mitsuru and Kokoro named her after this in honor of Hiro and Zero Two's relationship.

Ai was conceived when Kokoro admitted her yearning to bear a child to leave a mark for the future and Mitsuru comforted her after she was berated by Nine Alpha, leading to them sleeping together for the first time. Quickly, Mitsuru began to share Kokoro’s perspective on having a child and they began trying to conceive. However, they lose all their memories of each other as punishment for violating the rules on no intimacy between parasites. Ai was born on January 10th, 245 days after Hiro and Zero Two left in the warp gate. Although Mitsuru and Kokoro did not know what to do when Kokoro's pregnancy was first announced, Kokoro decided to keep the baby and Mitsuru was supportive of that because he said the baby had given him a reason to live. Despite the risks of piloting a FRANXX while pregnant because it would cause detrimental harm to the baby, Ai was born perfectly healthy, as this was due to that Kokoro was barely 4 weeks pregnant and quickly got the prenatal treatment needed.

When Ai was born, Mitsuru was so overcome with joy at becoming a father that he cried and Kokoro was happy to become a mother. Despite their rough start, MitsuKoko managed to form a loving relationship and take care of their newborn daughter. Kokoro and Mitsuru love their daughter dearly and Mitsuru dotes on her. She greatly resembles her mother, as she has Kokoro’s facial features and hair color, but she has Mitsuru’s eyes.

Ai seems to have telepathic abilities as she was the one who alerted everyone to pray for Hiro and Zero Two in space. When Ai is 18 months old and playing in the fields next to Zero Two's statue when she senses something is amiss. She runs up and pats Zero Two's statue, repeating the word "darling" over and over again, to the surprise of her parents, as she'd never learnt that word before. MitsuKoko surmises the statue of Zero Two is connected to Zero Two in space and call everyone to send their thoughts and prayers to HiroZero.

Ai is a lovable and precocious child who is loved dearly by her parents. She is a kind-hearted little girl from young, as seen when she comforted her mother Kokoro after HiroZero's sacrifice. In the MATO comic, Ai is also portrayed to be curious and enjoys listening to stories as she asked Miku to tell her stories about her parents.

Unnamed son

MitsuKoko had their second child, a son, shortly after HiroZero's sacrifice. He was first seen being carried around as a baby by Kokoro whilst she talked to Miku. He takes after Kokoro in looks - he had the same eye and hair color as her and seems to resemble her in facial features, making him Kokoro's 'guy version'. In the MATO comic, he is seen learning how to walk while his parents and older sister, Ai, encourage him. During the school ceremony, he sat on his dad Mitsuru's shoulders. His name is unknown at the moment.

Unnamed daughter

MitsuKoko had their third child, another girl, sometime after their second. While her exact age is unknown, she appears to be a toddler in the 10-year time skip. She was seen sitting on Kokoro's lap during the school ceremony, reading the picture book Zero Two illustrated. As her hair and eye colour and facial looks take after Mitsuru's, she is Mitsuru's 'girl version'. Given the significance of sakura in MitsuKoko's relationship, she was likely named Sakura.

Unborn child

10 years after HiroZero entered the warp gate, the parasites have a reunion during a school ceremony. When Ikuno, Ichigo and Futoshi chat, Futoshi mentions MitsuKoko are having their fourth child. As this fourth child is never mentioned or shown later, their appearance and gender is unknown.

Fanon
It is a highly popular ship in the fandom, having entered the weekly top 10 anime ships popularity charts and peaking at first place. It rivals FutoKoko, though the latter was sunk as of the Partner Shuffle.

The ship gained much popularity after MitsuKoko's first kiss, entering the top 10 list that week. The ship shot up from 7th place to 1st place the very next week after MitsuKoko consummated their relationship. MitsuKoko has the 3rd greatest number of fanarts of the Darling in the Franxx ships, behind HiroZero and IchiGoro.

When the ship started is often disputed. Some fans argue MitsuKoko only really started after the Partner Shuffle, while others claimed it started during the Beach Getaway or even as early as Episode 04 when Kokoro became concerned for Mitsuru's wellbeing.

The Darling in the Franxx fandom is quite divided on this ship. Some have applauded the ship's gradual development, while others criticized it for progressing faster than even the main couple of the show. Many of the ship's critics say they were too young to consummate their relationship and have children at such a young age, while fans say no legal age of consent existed in the post-apocalyptic world of theirs, so they weren't in the wrong. A few even went on to say MitsuKoko's act of rebellion was the first step in rebuilding the world. Other viewers simply dislike it because Mitsuru and Kokoro have completely opposite personalities, hence they didn't seem like a good match, while MitsuKoko shippers note how their personalities rubbed off each other towards the end.

Fandom
FAN FICTION

PIXIV
 * ミツココ tag on pixiv
 * ミツココ on pixiv encyclopedia

TUMBLR

Trivia

 * Kokoro is the first parasite to give birth to a child naturally in close to a century, and Futoshi proudly declared Mitsuru as the first parasite to become a father.
 * Kokoro's code number is 556 and Mitsuru's code number is 326. When added together, it gives 882. 882 can be read as "hahani" without the diacritic and means "to become a mother". With the diacritic, "hahani" becomes "papani" and means "to become a father". This foreshadows the birth and conception of their child.
 * With the kanji 反乱 ‎(hiragana: はんらん, romaji: "hanran”), "hahani" also means "rebellion". Consummating their relationship and conceiving a baby were acts of rebellion against APE as Papa had banned any relationships besides FRANXX partners.
 * Kokoro and Mitsuru are the youngest parasites to parent a child, as Kokoro was 15 years, 7 months old and Mitsuru was 15 years, 11 months old at the time of Ai’s birth. At the time of her conception, Kokoro was 14 years, 10 months old and Mitsuru was 15 years, 2 months old.
 * Kokoro’s name means ‘heart’ and Mitsuru’s name means ‘fullness’ in Japanese respectively. Their daughter’s name, Ai, means ‘love.’
 * These words can be put in a sentence too - My heart is full of love.
 * Although Mitsuru wasn't interested in Kokoro until after the partner switch, it is implied he has been physically attracted to her; in the first Drama CD, Ikuno teases Mitsuru for staring at Kokoro’s thighs while Miku falls asleep on Kokoro's lap. Upon hearing this, Mitsuru blushes and adamantly denies this while Kokoro is embarrassed.
 * Kokoro was already pregnant with their daughter at the time of her and Mitsuru’s wedding. But her pregnancy is likely to have been shortly after conception but prior to implantation, as implantation takes place 7-9 days following fertilization. This could explain why APE never detected her pregnancy during the memory wipe or else it’s likely they would have done a termination before returning them to Squad 13.
 * Due to feeling pain in their heads after saying each other’s names, Kokoro suggests she and Mitsuru refer to each other as ‘Mama’ and ‘Papa’. However, Mitsuru still tends to call her by her name, as her name is important to him as a reminder of their past.
 * Kokoro and Mitsuru were each other’s first kiss and the first pair to consummate their relationship.
 * They are also the first pair to get married and start a family.
 * The most seen flowers in the greenhouse where Kokoro and Mitsuru spend time together heavily imply their relationship; Red Lotus, which symbolizes romantic love in reference to their growing feelings. Red Hibiscus, which symbolizes gentleness in reference to how Kokoro treats Mitsuru. Cactus, which symbolizes lust in reference to their sexual relationship (it also means maternal love in western culture). The presence of Cherry Blossoms during their wedding is in reference to them starting over after their memory erasure, as cherry blossoms symbolize renewal and transience of life.