**Background:**
In Season 1 Episode 5, it is discovered that during her first year of high school she started an idol group. However, one by one the members gave up because Nico's standard for idols was too high for them and they couldn't keep up.
In Season 2 Episode 4, it is revealed she has two younger sisters named Cocoro and Cocoa, and a younger brother Cotaro. Nico's father has been out of the picture, and so her mother is constantly out of the house in order to work and financially provide needs for her four children. Due to being in a single-parent household, money is tight and their living space is compact. Because Nico's mother is nearly never home, Nico has long since assumed the role of their household's head (or possibly sole) caretaker. Nico is the eldest by the largest age gap, with her three siblings being all much younger than her and closest to age with each other. Because of this, Nico is accustomed to and skilled in cooking and housekeeping. Most importantly, however, she seems to care very much for her younger siblings, and will do anything to make them smile. She will go as far as to lie in order to make them happy. This is discovered when Nico's siblings express their belief that the other members are Nico's backup dancers, which was a lie that Nico told them and substantiated with altered μ's posters in which she was the center (switched with Honoka). Unaware of the truth, Cocoro, Cocoa, and Cotaro act happy, proud and inspired by the idea of their oldest sister's unparalleled success.
All of this information comes as a surprise to the other members, as it runs contrary to her often self-centered behavior at school and during idol work. However, the revelation of Nico's home life provides insight as to why Nico's specific personality traits and values developed and how they inform her behavior within μ's. Her brazen desire for the spotlight and to be doted on is a product of not being afforded such attention due to her home situation. Nico's obsession with making others smile with her catchphrase ("Nico Nico Nii!" or にっこにっこにー) is related to when Nico would try her hardest to cheer up her family members during hardships.
Nico's special skill is hair arrangement.
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**Personality**:
Normally, Nico has quite an abrasive personality, but when she takes on her alternate personality, she becomes a happy, upbeat character who is always smiling, often saying her catchphrase, "Nico Nico Nii!" (にっこにっこにー), accompanied with a pose. She usually thinks a bit highly of herself but, despite that, she is also caring.
It is later revealed in Season 2 Episode 4 that her obsession with performative, over-the-top happiness and cuteness is because of the difficulty of her home situation. Her family circumstances and the role she plays in it have led her to fixate on both making sure as many people as possible are smiling and also seeking and receiving attention and praise. This manifests in her idol obsession and subsequent persona.
A common joke in the series is that she's often ignored by the other members of μ's when she claims that she is the better idol. An example of her trying to make the others believe she is the better idol is in Season 1 Episode 10 when Nico claims that she has a personal chef like Maki and has never cooked before. Kotori falls for the lie unknowingly. However, she accidentally forgot about her lie when it was dinner time, and ended up cooking for everyone to reveal the truth.
Sometimes, her determination to become the best idol causes her to be a little bit cold, calculating, and somewhat ill-intentioned. An example of this is in Season 1 Episode 6 where she is seen suggesting that the girls hold a karaoke and dancing competition, hoping to outshine the others, so that everyone will accept that she is the better idol and to be able to claim centre position.
Nico often gets annoyed with the former student council president, Eli Ayase, for taking away the spotlight from her with Eli's beauty and maturity.
She also argues a lot with Maki, since their personalities often clash together. However, they have a good friendship and they actually care about each other.
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**Appearance:**
Nico has long black hair that she ties into twin-tails and crimson eyes.
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**Club Role**
Nico served as the President of the Otonokizaka Idol Research Club until her graduation, at which point she passed the title to Hanayo. She assists Kotori with costume design.