MitsuKuno

MitsuIku is the het ship between Mitsuru and Ikuno from the DARLING in the FRANXX fandom.

Fanon
Mitsuru and Ikuno have known each other since they were small children living in the Garden but they had very little interactions with each other. When they are 14, they are assigned to the same FRANXX squad and, after passing their capacity test, they are paired up. However, they quickly developed a strong dislike towards each other.

During their startup ritual, they successfully synchronized and activated Chlorophytum. He was unfazed as Ikuno panted from the initial pain of the synchronization. However, right before the squad's first battle, they attempt to synchronize but fail as Ikuno isn't able to do it. She pleads for more time but Mitsuru tells her not to bother. Nana later asks what happened and she contributes to Ikuno feeling unwell. Mitsuru asks if they are incompatible but Nana says that happens a lot during the first time and it's not a reason to split them up, much to his disappointment. When the squad is cornered by a horde of klaxosaurs and Hiro is declined to ride with Zero Two to save them, Mitsuru volunteers to ride with her but Nana is hesitant because he won't be able to handle Strelizia. He persists because the others will die but Zero Two refuses until Hiro reluctantly tells her to go with Mitsuru. As he leaves, Mitsuru reveals he just really wants to prove he can pilot Strelizia better than Hiro. During the battle, he becomes empowered by the expietence and parades how Zero Two is a better partner, along that he wouldn't mind being her official partner, which deeply upsets Ikuno. At the end, he is left severally wounded and traumatized.

While Mitsuru is in the hospital recovering, Ikuno is still upset by his words and that she couldn't pilot. Ichigo assures her to be there for Mitsuru as his partner. When a klaxosaur appears, Mitsuru attempts to get out of bed to join the fight despite being wounded and Ikuno tells him not to but he doesn't listen. She offers to help him but he refuses and ends up collapsing in her arms. She helps him up and they get into Chlorophytum. He says he hope she can activate it with him and she tells him not to worry. Thinking of Ichigo, she is able to synchronize with him and they activate Chlorophytum. In the manga, he takes his criticism towards Ikuno more boldly by describing her as incompatible with him while he talks with Zero Two.

A few weeks later, when a klaxosaur sprouts mysterious goo all over the FRANXX units, the goo falls into the cockpits and onto the girls, causing their suits to melt. Mitsuru has no reaction other than a small tint of blush as Ikuno is exposed. When the girls find out what happened, Ikuno freaks out and tells Mitsuru not to look at her but he says he isn't. He later blames Ikuno the mission failed and that Chlorophytum malfunctioned because she freaked out and, while she is worried about Ichigo being absorbed by a klaxosaur, Ikuno agrees and starts crying. Mitsuru starts to double down as he sees her cry and shifts the blame of the mission failure to Zero Two for acting out against orders.

Shortly after, during a briefing, Hachi reports that Mitsuru and Ikuno's sync rate has fallen, along with their killing numbers. While guarding an S-Planning facility, Chlorophytum deactivates and Ikuno finds Mitsuru ill. While he is recovering, Ikuno reveals to the others that his health has been fragile due to that he underwent an Elixir Injection when he was a child. Upon recovering, they undergo a capacity test, which shows their paracapacity rate has fallen lower and, as it is shown that Mitsuru is the source, Nana proposes the squad try a partner shuffle. While everyone debates, Ikuno agitates Mitsuru for acting so cool when he knows full well that's this is his fault and he just wants to be acknowledged. After everyone discusses it, Ikuno asks to try riding with Ichigo, who is surprised and hesitant but agrees. Kokoro then asks to try with Mitsuru, which surprises everyone. While testing their paracapacity, Ikuno and Ichigo fail to connect and time out whereas Mitsuru and Kokoro manage to maintain a low but stable connection. Because of this, Kokoro is paired with Mitsuru and Ikuno is paired with Futoshi. While in the hallway, they run into each other and she tells him he can laugh at her but he doesn't respond.

Following the partner shuffle, the two slowly became more civil with each other, likely because they no longer had to put up with each other while piloting together. Overtime, Ikuno notices a change in Mitsuru's demeanor following his partnership with Kokoro, how he has went from a sarcastic and stoic person to smiling and interacting with everyone more. What catches her attention the most is that his hair was suddenly cut and Kokoro confirms she cut it, and Ikuno admits she thinks it looks good on him. This makes Ikuno suspect that Mitsuru and Kokoro have developed a romantic relationship. When this is confirmed after Zorome reveals he caught the two in a compromising position (Kokoro attempting to unzip his uniform to initiate sex with him), Ikuno admits she isn't surprised at all. Nine Alpha shows the squad the baby book Kokoro has been hiding and berates her for wanting to have a baby because humans have casted their gender aside for evolution and is a nuisance. This deeply angers Ikuno and she slaps Alpha, surprising everyone.

A while passes, and when Hiro announces Kokoro and Mitsuru have decided to get married before they all have to leave for the Bird Nest, everyone is supportive but Ikuno is sullen. During a talk with Ichigo, Ikuno admits she didn't lash out at Alpha to defend Mitsuru and Kokoro but that his words offended her because she is in love with Ichigo. The next day, before the wedding begins, Ikuno gives Kokoro a bouquet of flowers and pins some flowers on Mitsuru's uniform, and they both thank her and she goes to sit in attendance as the wedding starts. However, the 9's and an APE assault team interrupts the wedding and takes the two away. A couple of weeks later, Ikuno and the others are devastated to learn that those two's memories of each other have been altered, and Ikuno is upset the wedding they all worked so hard on was ruined. She is slo worried they will never regain their memories when Papa explains why he ordered the memory erasure and it is impossible to return the memories.

A few days later, Ikuno and the others are shocked to learn that Kokoro is pregnant with Mitsuru's child but she is supportive of them when they decide to keep the baby after they reconcile. Eight months later, she is present for the birth of their daughter, Ai, and she happily smiles as Mitsuru meets and bonds with his newborn daughter.

Two years later, Mitsuru helps move research supplies into Ikuno's office and saves her when a stack of books almost fall on her. She thanks him and mentions how she is going to ask for Dr. FRANXX's research files. He advises her not to push herself despite the advances her research may have. Ikuno laughs and winders why they are human. She then mentions all the things that happened to Mitsuru and now he is a father. She admits she is happy for him for having someone he loves and he is moving on with his life. Mitsuru asks her about herself and she says she has chosen to surrender herself to her accelerated aging process, but she intends to live as long as possible with everyone else. This shows that the two have truly reconciled and become genuine friends.

Fanon
This shipping is not very popular due to Mitsuru and Ikuno's mutual dislike for each other, and the fact that both have other love interests. Even when the two reconcile, the shipping failed to progress, especially following the pairing of MitsuKoko and then IkuNao.

Trivia

 * Mitsuru's English voice actor, Bryson Baugus, is a MitsuKoko supporter whereas Ikuno's English voice actress, Leah Clark, likes both MitsuKoko and IchiIku.
 * According to Ichigo, Ikuno may be the only person who understands Mitsuru the most, due to both having personal problems they feel they can't talk to anyone about.