As the title suggests, the whole anime revolves around mermaids. Akeno however, belongs to an enforcement unit of the mermaid society and she actually keep tracks of the mermaids to ensure that they conform to the rules and make sure that they blend into society.

Having shoulder length front hair and a ponytail that reaches the nape of her neck, Akeno has a pine-like shade of green. Originally introduced as a fierce disciplinarian, Akeno eventually grew a soft spot and even felt compassionate towards her peers. Disregarding her job, Akeno was even shown to be quite docile in contrast with her strict personality at first.

Introduced only as a supporting character, no one knew that this office clerk of a talent agency will garner her own fan base despite not being an idol. She is shy, a daydreamer and loves sleeping. What's there NOT to love about her?

Kotori has relatively short hair (reaching just above her shoulders), she has bangs that covers her forehead and her hair is coloured a dark shade of green. Her green hair are similar to her traits as she is calm and docile, to the point of being meek. She is also an easy person by nature and honestly, it is always a refreshing experience to see her have some screen time after the idols.

We think that this character can be considered a mad scientist. However, the whole premise of this show is mad anyway, so she is perhaps the most normal of them all. Fuwa aspires to be a scientist in the art of sex. In a world where the concept of dirty jokes do not exist, it is no wonder that science will be curious to explore the unknown. She will constantly bug everybody with inappropriate questions just to further her research.

Fuwa has long hair that reaches to her back. She also has long wavy hair. That and her hair colour reminds you of seaweed giving her an unkempt look. While not actually fitting into any broad description of having green hair, the loyalty of Fuwa eventually switches to the protagonists and she aids them during their times of need. It is a main trait of a green haired characters to be a loyal supporter to the main characters - a trait of healing skills as they are support by nature!

Despite having a weak constitution, Asa doesn't rely on others like most of the weaker and sicker characters. She is cheerful and happy most of the time and loves cooking. She is one of the main heroines in this rom-com, so she is a bit shy with her feelings.

Her short green hair, tied up in a ribbon and dyed a brilliant shade of chartreuse expresses her trait of rejuvenation. Despite being sick and frail, she does her best to herself and the people around her, happy. She is energetic and lively and also a bit of a tomboy as well. Definitely not the traits of a sickly character!

The main protagonist of the story, Eureka is a pilot of of the NirvashTypeZERO. Appearing distant and aloof at first as well being blunt with her words, Eureka eventually grows to communicate more with humans, being able to understand and express emotions as well.

Eureka growth is similar to that of a robot learning the human emotion. Eureka is not fully human but more of a humanoid. She had a hard time at first dealing with interpersonal issues and even questioned them. Eventually, a revitalization of her character shows us a newer side to her, one that is more sympathetic and understanding towards others. Eureka has very short hair, her hair is pinned up in front and she has a very light shade of green

A bubbly singer, a hyperactive child, cheerful and optimistic is what describes Ranka. This positive individual brings joy to the world. Yet, she harbours a dark past and it can even be said that she wears a mask to conceal her true emotions most of the time.

While her positivity and energy is merely a facade, Ranka is a highly developed character as much emphasis is placed in exploring her persona. She has short hair (and an ahoge!) and has a nice dark shade of juniper green. Like her green hair, she shows a calm, peaceful and happy exterior, but behind the foliage of a forest lies a hidden and dark secret. Nevertheless, she is still a lovable character!

Rarely speaking and having hawk like eyes, Minami is thought to be scary and unfriendly. However, she has a very kind side to her and cares deeply for just about anybody. Even amongst friends, she doesn't speak much and is easily embarrassed when others remarked about her kind nature.

Minami plays the role of a loyal support. She won't leave her friends behind and would rather not be recognised for any of her kind deeds. Her warm personality brings comfort to the people around her especially her best friend in the series, Yutaka Kobayakawa. Minami has short and bright lime green hair

Simply known as Tsuruya in the series, she plays the support role in the anime and is the close friend of the popular Mikuru Asahina. Fun, bubbly, cheerful and hyperactive, her personality won her a fan base despite being a side character. In addition to her cheerful personality, Tsuruya also has a peculiar but adorable speech pattern by leaving a syllable out when she speaks some times.

Tsuruya upbeat attitude shows the rejuvenating and refreshing side to the series. The side character's role after all is to add comic relief and provide light heartedness to the series after prolonged exposure to the same storyline. She has a darker shade of green, almost like a clover long, waist length hair which flows freely . This is the reason as to why we are putting her on Number 3.

Next on the list is the Sonozaki twins. During the course of the anime, if you are unable to discern between the two, don't worry, you're not alone. While there are much confusion, there is a way to discern between the two. Mion is the more tomboyish and rash twin whereas Shion is the more refined and shrewd of the twin.

Due to the premise of the story, both twins have equal dark secrets to hide. Their green hair is a representation of the secrets they harbour and they both appear fun-loving and innocent. As the story progresses, their history and dark pasts comes to the surface which comes as a total shock to many of fans of the anime. Both of the twins have long bright mint green hair but while Mion keeps her hair tied up in a long ponytail, Shion keeps her tied up with at back with a ribbon.