There's a lot to say about this, including questioning their degree of blood relation. But the bottom line is, in Japan, where the story is set, there is no legal or customary prohibition against cousins marrying.
Bottom line: As an online parody of 4Kids meets Elfen Lied says, if it bothers you to distraction, think of them instead as childhood friends.
What is the ultimate fate of Kurama?
That depends on whether you watch the anime or read the manga. In short, the anime has him die along with his true daughter, Mariko, to atone both for his treatment of her and his euthanizing of many Diclonius infants. The manga makes this more complex, with Kurama, at first wishing to die, but then realizing that he should atone by living and making up for his sins as a living man.
Bottom line: The man had much to answer for, and each version has him do so in different ways.
Are Diclonii naturally violent?
Both the anime and the manga are perhaps deliberately unclear on this subject. There is evidence on every front with which to make the nature versus nurture argument--Nana, being a huge part of any such debate. One of the major problems in making this determination is the way Humans do discriminate, even against each other, and the young age most of these girls are when their powers awaken.
Bottom line: Approach a Diclonius and find out (but have your will on order and start a family beforehand).
Does Lucy live or die at the end?
At the end of the anime, it seems likely she is still alive, and is likely the person standing behind the door that Kouta goes to answer. The events at the end of the anime strongly imply that the events of the later parts of the manga are still to come, and even if Kurama isn't needed somehow, Lucy is. In the manga, her power grows to such a state that massive use of that power in several battles and then to heal the dying Kouta destroys her body's integrity, causing it to melt. In a last act of mercy and love, Kouta kills her to end her pain and agony.
Bottom line: Neither scenario looks good for Lucy...in this life.
If The Kakuzawas are Diclonii as well, why doesn't Lucy want to ally with them?
Since Diclonius means two horns, technically, the Kakuzawas (except for Anna) are Diclonii. But they are not of Lucy's species or, if you will, subgroup/offshoot of Humanity. The Kakuzawas are actually ordinary Humans born with a minor genetic mutation. They never had powers or any other thing that made them more than Human. True Diclonii can sense one another's presence, but Lucy never sensed any such presence from either Professor Kakuzawa or his father. Since the revealed Kakuzawa family history included tales of their persecution by non-horned Humans in feudal Japan, it seems likely that the racial and eugenics stories the family told were just that, stories meant to rally the morale of a people who were hunted and hated by others.
Bottom line: Lucy didn't want them because they weren't part of her kind.
Are there any male Diclonius or are they an all-female subspecies of normal Humans?
There are indeed males but they are so extremely rare that we never see one in the anime and in the manga we see only one Male Diclonius, who is Lucy's half brother. Very few knew of him and those who did were convinced that he was one of the only males in existence. The series offers no evidence one way or the other, yet more males could have been in hiding, or simply have gone unnoticed by sheer low numbers. Bottom line : They must have continued to be rare, because Kouta's narrative in the final chapter indicates that while the Diclonius War was incredibly brutal and decimated much of the Human population, it did not last long. Primary monarch-level males and females breeding would have changed this.
Bottom line: They are described as rare, and only one is shown in the series.
Why does Elfen Lied have so much ecchi content?
There are multiple instances of naked flesh and sexual situations. Elfen Lied has these and so does life. Lucy, as Nyu, is a totally innocent girl, unaware of the impact her antics have on everyone, especially Kouta. The nudity of the Diclonius girls inside the facility speaks to their inhumane treatment as experimental test subjects. A good example to think of is the anime-only scene where Kouta runs to rescue Nana from Mariko. She has been stripped naked by Mariko, but his only concern is for a member of his family. Her prosthetic limbs even put him off more than anything.
Bottom line: The ecchi content is like the gore and violence - raw, and part of the core of Elfen Lied. It is up to the viewer/reader whether this content wholly overwhelms the other areas of worth in this story.
Who are the twins at the end of the manga?
It would seem, and it is widely agreed, that they are the reincarnations of both Lucy and Nyu, and, with a new life, comes innocence and redemption. Many, many, MANY questions abound as to the Five W's and H in this matter. Are they Diclonii? Human? Who are their parents, or did Lucy's death burst of power to create them somehow? Will Kouta treat them as friends, or will they pursue him as they come of age? What will Yuka think? If we treat Lucy and Nyu as separate souls, could the original Kaede be Kouta's daughter Nyuu Junior?
Bottom line: The twins are hope. Hope that love and friendship can triumph over any and every obstacle. An appropriate end for the rollercoaster ride that is Elfen Lied.
Why isn't Nozomi in the anime?
The basic opinion is that director Mamoru Kanbe didn't want her there. Whether this was from an actual distaste for the character, or simply feeling the story flowed better without her, is somewhat in dispute.
Bottom line: When watching the anime, remember this line from the 60's group, The Zombies - "Please don't bother trying to find her; she's not there."
Did Nana marry Kurama, did Mayu marry Bando, and isn't the indication of their relationships a bit off-putting?
One theme that runs through many an anime/manga is the ferocious devotion and love a young woman can feel from a very early age, and the lengths she will go to while pursuing that one true love. This doesn't always work out neatly, as both Yuka and Lucy could tell you, as could Love Hina's Mutsumi or Tona-Gura!'s Kazuki or...you get the point. Mayu has been said to be unwilling to touch a man after her traumatic experiences, and was afraid even of Kouta at some points. The man she has seemingly chosen can never be with her in an intimate way, due to his massive injuries. The likelihood is that whether Mayu gained a future husband in Bando is less important than the fact she was right about him: The seemingly monstrous being had a caring heart within. It was a heart her parents never showed her, and it left pain Kouta and Yuka could only partly help with. Only gambling and winning on Bando could give her back her belief in better things to come. As for Nana, her relationship with Kurama did evolve over time. She will continue to age rapidly, and Kurama will never sire children again, and emotionally, Nana is one of the only people left he connects with.
Bottom line: Lynn Okamoto never reveals the exact fate of any character except for Kouta. Nyuu Junior could be Mayu or Nozomi's daughter, for all we know, though this seems highly unlikely. We don't know who married who, or if anyone married anyone, for that matter.
Why is X (Kouta, Yuka, Nyu, Nana, etc.) so Y (dense, tense, pushy, optimistic, etc.)?
The characters in Elfen Lied can also be viewed as deconstructions -- which is to say, hard discerning looks -- at the basic character types in many anime. Kouta's denseness could be that of a typical harem manga hero, walking proudly and slapsticking along with the likes of Keitaro Urashima and Tenchi Masaki. Or--is this the personality of a young man who had to shut down part of his memory to regain his sanity? Is Yuka just that uptight, or would anyone start to get nervous when their childhood dream is wrecked by crazy circumstances? Is her devotion to Kouta proudly in the tradition of great romances, or something she should have let go of and moved on from? Is Nyu's grabbiness and lack of modesty ecchi hilariousness, or is it something that makes Kouta's life impossible, and traumatizes poor Nozomi, for example? Are we supposed to see Nyu's antics as arousing sexual fun or take another look at every girl who grabs another girl in the anime bath, despite being told to stop? Nana's optimism is heartfelt and charming--until you realize that this is mostly a defense against living a life of horror and deprivation in which your only link is a father who largely permits this to happen. Is Kisaragi's savage murder a shot at clumsy girls in anime, or a marker that shows us such girls would have trouble living in a world of killers?
A classic example is this : Were Brutus and Cassius and the other conspirators in William Shakespeare's Julius Caesar heroes stopping a tyrant, or criminals depriving Rome of its chosen leader and causing chaos?
Bottom line: X is so Y for a reason. It, however, is a reason that, like as not, no two people will ever completely agree on.
Will the anime see any manner or sort of follow-up?
There is no word from the various rights-holders, and the net is fairly choked with requests and ideas for a Season 2 or a remake, like was done for Full Metal Alchemist. These things take money, and whether or not those with the legal power to do so want to spend their money that way is a question we simply have no answer for.
Bottom line: Unlikely but NOT impossible. Don't count on it, but never discount it, either. Anything is possible, and some things are more or less likely than others.
How can Mayu's mother be so horrible and cold to her, when she has suffered like that?
Some people have a sociopathic level of detachment from all others, caring only about their own needs and wants. To her mother, Mayu was now an obstacle to her happiness. Selfish is almost a euphemism when talking about her.
Bottom line: To paraphrase Rod Serling's narration at the end of 'I Am The Night - Color Me Black' - Don't look for what happened to Mayu in the pages and episodes of Elfen Lied - look to the world around you. There are shelters and services that try and aid kids like Mayu. Give to them.
Why does Diclonius hair vary so much?
In the manga, Lucy/Nyu's hair is a reddish pink ; Nana's is a purplish blue, or a bluish purple ; Mariko's seems to be blonde. Two of these are not natural Human hair colors, and the third is not a usual color for a child of strict Japanese descent. We see no other Diclonius in color illustrations. While Pink and Blue are hair colors seen in other anime, no Humans in Elfen Lied seem to have them, so they too are a part of the Diclonius mutation, though why something like hair would differentiate so much remains a mystery.
In the anime, all Diclonius have more or less the same shade of pink hair. This is probably to identify such characters quickly and easily for the audience, since in certain scenes, their horns may be harder to discern than in others. A visual reminder like this keeps the mind of the audience inside the fictional universe. In two inverse examples, both the Teenage Mutant Ninja Turtles and The Real Ghostbusters used color-coding on their uniforms, whereas the sources these cartoons were adapted from had all team members in one color and style of uniform. This was lampshaded for the Turtles in their 2009 Crossover Special, and for the Ghostbusters in the cartoon episode 'Citizen Ghost'.
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