Nico Niiyama

Nico Niiyama (新山 仁子 Niiyama Niko) is a main character and one of the group of seven kiznaivers in the titular anime, manga and novel series.

She resembles the sin of Greed. In modern Japan, her sin is 'The Eccentric Headcase' (Japanese: 不思議メンヘラ, Romanized: Fushigi Menhera, Official English Translation: "Screw Loose"). Her identification when she experiences pain is D-6.

Character Outline
A girl whose fashion and behavior are very unique. She has a screw loose that she is a so-called Eccentric-chan (ふしぎちゃん, Fushigi-chan, lit. "an eccentric and spontaneous young girl").

Although she is known by her classmates as of the beginning of the series for claiming to commune with fairies, her deepest secret is revealed to be that she doesn't even believe in fairies.

Appearance
Nico appears to be short. She has bright orange hair with teal streaks which are tied into two pigtails on both sides of her head. She has jagged-cut bangs, with the fringe on her left shorter than on her her right. On her right pigtail, her hair is tied with a fluffy pompom with eyes and a bright pink ribbon. On her left, her hair is tied with a similar pompom with hearts sticking out of it. She has round purple eyes and little eyebrows.

Nico usually wears the basic school uniform, dolled up with a yellow petticoat, bunny lanyard, yellow belt, bunny backpack, and bright mismatching socks. Her appearance is bright and colorful, similar in fashion to fairy-kei and decora. She appears to be 150 cm tall.

Personality
Nico appears to be bright and energetic, often being the comic relief of the series. She tends to overreact or be very dramatic when experiencing new things, and acts very immature and girly.

However, Nico is shown to be rather perceptive in the series, much to her companions' surprise.

Since she came from a wealthy family, it is implied that she has polite and lady-like manners.

Honoka Maki
Due to the death of Maki's friend Ruru, which Maki blames herself for, she had distanced herself from everybody, refusing to be friends with Nico who had asked her to be her friend. However, the kiznaivers had found out about Ruru, helping her to find out about the true message Ruru wanted to give to Maki and giving her strength to make friends. Maki would be closest to Nico, since she was the first to approach her as a friend.

Hajime Tenga
Nico is romantically attracted to Tenga. These feelings begin to develop as far back as episode 5 or even earlier, but are only fully showcased following episode 7. Her feelings for him are not really explained beyond being "weird taste [in guys]," but Nico seems to become very energetic and excitable around Tenga every time they interact, so the source of her feelings can be easily inferred.

When her feelings are exposed to Tenga during the Storm Arc, Nico is understandably humiliated. Even though she knew that Tenga liked Chidori and would most likely fight for her, she still wanted him to choose her over Chidori deep down, but couldn't bring herself to say it out loud even when the kiznaivers were sharing inner thoughts.

Despite appearing to ignore her feelings during the Storm Arc, Tenga is consistently shown throughout the series to care about Nico in his own unique way, possessing protective instincts toward her, as well as a secondary attraction. Tenga and Nico's temperaments are also similar, and they find themselves agreeing on most things. Although the Storm Arc does a poor job of addressing this, it is heavily implied in the episodes following that he thought a lot about not only his and Chidori's romantic feelings, but Nico's as well. Even so, the fact that Nico expresses in the finale that she "hasn't given up on Tenga" and still has plans to pursue him suggests that he never explicitly rejected her, thus leaving his feelings for her open-ended according to his own logic.

Even so, when Nico sees Tenga and Chidori talking at the mall in the finale while waiting for her, Hisomu, and the others to show up, Nico sees how well the two of them are getting along and decides to let them have the moment alone, rationalizing this by stating that at the very least, she doesn't want things to remain awkward between the two of them. She still expresses feelings of jealousy, however, and reaffirms her feelings for Tenga in the form of planning a playful "fistfight vs. Chidori on the beach" for Tenga's love, and to bring everyone even closer together.

Noriko Sonozaki
Among the rest of the kiznaivers, Nico disapproves of Noriko and Noriko is indifferent towards Nico. Nico makes it clear to the kiznaivers that she honestly doesn't care for Noriko, no matter how tragic her past is. At the end of the last episode, Nico tries her best to be friendly toward Noriko and invites her to take purikura with all of them, as Nico generally wants to be nice and sociable with people.

Quotes

 * "I don't believe in fairies!"

Trivia

 * The name Nico means "compassionate" (仁) (ni) and "child" (子) (ko).
 * Nico's surname Niiyama means "fresh, new" (新) (nii) and "mountain, hill" (山) (yama).
 * The original Deadly Sin that Nico embodies is Greed (avaritia) and the Heavenly Virtue she achieves by the end of the series is Charity (caritas).
 * The term menhera used to describe Nico's modern-day sin in Japanese has a double connotation in modern Japan. It can be a highly loaded and socially damaging slang term (typically applied to young women and ex-girlfriends struggling with mental health) that can be boiled down to "a person who has a few screws loose/an extremely stressful person," but can alternatively be applied to "one (regardless of gender) who dresses up in a sickly cute style." For more information on menhera in English, read here and here.
 * In episode 2, it is revealed that Nico does not, in fact, believe in fairies.
 * In Episode 9 and again in Episode 12, Nico confirms that she has romantic feelings for Hajime Tenga.
 * Nico often speaks childishly, referring to herself using third person pronouns more often than using "I," "me," etc.
 * In Episode 2, it is said that she partially pretends to be eccentric since according to her she is "smart," "rich," "cute," and has "a perfect life," and doesn't want to be ostracized or dissed by her peers for it.