Relations[]
Naota[]
Ninamori seems to have a crush on Naota, first indicated by playful teasing and jealousy towards Mamimi. In the third episode, she goes so far as to rig the votes just to have him cast as her co-star in the class play, and even confides the secret to him when they are alone. She feels a meaningful connection to him, noticing their shared distaste for the fake maturity that adults emulate throughout the series, but mistakenly attributes his reason for developing this view. This mistake is the reason she selected him and rigged his votes, as the character he will play displays Ninamori's view. She compares him directly to his character when opening up to him via the quote, "He hides who he really is and pretends to be someone else forever, but in time becomes that person, so his lie becomes the truth, see? He transcends the mask. Well, don't you get it? That's how he finds happiness." However, Naota can't understand that reasoning because he didn't develop his worldview that way. While Ninamori gained it from the chaos that is pretending to be the successful daughter of a mayor who cheats on his wife, Naota simply hit a wall with maturity that created a disdain for people who fake what he desires. The misunderstanding results in a break in the romantic tension between them and later culminates in their fight as their respective immaturity clashes. Notwithstanding, she values the understanding they have and gains a better grasp of her own struggles because of him. Naota, meanwhile, treats her with a bit more respect than he does Mamimi or Haruko, sympathizing with her family issues and calling her "very grown up" at one point. They do not take any further steps toward romance, however, until the final episode.
Haruko[]
Ninamori does not meet Haruko until the third episode, and her first impression of her is a strongly negative one. However, although it's clear Ninamori has some jealousy of her relationship with Naota, she doesn't do or say much about it later.
Mamimi[]
Ninamori does not interact with Mamimi at all, but from hearing about her being called "Naota's wife" and seeing them together, she is quick to judge her as a ditzy airhead. Her opinion of Mamimi seems to change slightly when she notices how Naota's closeness with Haruko is hurting her.
In the novelization of "FLCLimax", she became angry at the high schooler after finding Takkun out in the rain by himself, suffering from a leg injury and malnourishment. After seeing Mamimi struggling to find cat in the riverbed the following week, Ninamori tells herself that Mamimi will never find the cat now, as she is taking care of him at the Ninamori residence and that Mamimi should learn to be more responsible if she ever plans to get a pet again.
Masashi and Gaku[]
Gaku and Masashi are probably the closest friends Ninamori has besides Naota. They call her "Ninamo", she hangs out with them during and after school, and even gets a part-time job making deliveries with them in the fifth episode. By the end of the final episode, they start showing signs of being attracted to her, though she still seems more interested in Naota.
Kamon[]
While not discussed as much in the anime, in the novel, she is initially disgusted with him after he had given her a copy of Come On Mabase. Referring to him as a shady-looking middle aged man, she is disgusted by what he wrote about her family and questions why he would give the magazine to someone who is clearly in elementary school in the first place. She is more horrified after finding out that he is Naota's father and that he actually knew who she was when he gave her the issue. During dinner, Kamon insisted that she could stay the night and he would her call her parents to let them know, but she told him that her and her parents live separate lives, so there would be no need for him to do that.
As she bathed at the Nandabra residence later that night, he suddenly spoke to her from a nearby glass partition, forcing her to quickly cover her chest with her forearm (in the novel, she further noted that he was actually peeking in and she could feel him scanning her nude body with his eyes). He asked if she resented him for writing the exposé on her family. Despite viewing Kamon as a creepy pervert, she does express her gratitude towards him, as his exposé got rid of her father's secretary. He then praised her for acting like an adult and handed her a shower hat.
Mayor Ninamori's Secretary[]
Although she is only briefly shown during "Marquis de Carabas", the dynamic between Ninamori and her father's secretary is civil yet tense, as Eri is aware that the secretary is having a relationship with her father. In the novelization, she seems to be more resentful at the secretary compared to the anime, fully blaming the woman for her parent's relationship falling apart.
After their affair is made public, the secretary quickly flees town, with Ninamori being described as having hatred in her heart as she watched the woman make her escape. It also noted that she wanted to be the one to get the secretary kicked out as her way of revenge rather than seeing her flee in an act of cowardice, before finally calling her a "perfumed hag".
Mayor Ninamori (Father) and Mother[]
Ninamori wants her parents to stay together desperately, to the point of rigging a play's election so she'll be the lead in an attempt to force them to see it together for her sake. In the novel, she fondly remembered the times that her parents were in love and how her father would constantly thank her mother for supporting him as he struggled to become mayor of Mabase. She then remembered the day when her father explained that despite still caring for each other, he and her mother will live in separate houses now because of the fuss it would cause if they had a public divorce and that it was "an adult thing". Seeing the secretary standing right next to her father as he tried to appease Eri made her even more upset.
In "FLCLimax", during gym practice, she tells her classmates Masashi Masamune and Gaku Manabe that she had finally talked to her parents the day before the play, and let them see her cry as she told them how she truly felt. She further noted that in the moment, she had stopped acting like an adult and returned to just being a child, hoping that Naota would learn to do the same.