Seinen anime tend to have much more intricate plots than shonen ones do. This is usually due to the growing age demographic and the belief that entertainment should age with the audience.
That isn't to say you cannot find entertainment in whatever way you please, only that more options are available. This article will profile the ten darkest plotlines in seinen anime and rank them for how dark they are.
Note: This article will contain spoilers for the anime on this list. This article is also just the author's opinion. Content warning for plotline discussions of a mature nature such as violence, s*x, and other such topics.
10 darkest seinen anime plotlines including Kill la Kill and Code Geass, ranked based on dark content
10) Kill la Kill
Studio Trigger's seinen anime Kill la Kill does feature some rather dark content in its narrative. It's the story of Ryuko Matoi, a girl with one half of a scissor blade she found impaled in her father, trying to track down her father's killer whilst battling through the hellscape that is Honnouji Academy.
But surely, how dark can this get? The big reveal starts in episode 11 and the revelations don't stop there. In a nutshell, the plotline took a hard right turn as Satsuki Kiryuin wasn't the villain. She had to endure years of hell from her mother Ragyo Kiriyuin and her elitism schtick was an act to betray Ragyo and stop the Life Fibers.
The gist of Ryuko's side was that she was Satuski's sister and not human, Ragyo killed their father, Senketsu is alien clothing given sentience, the aliens were using Earth to reproduce and spread, and Ryuko had to team up with Satsuki to ensure their mother's plans never succeeded.
The bath scene and Ryuko's brainwashing scenes are comparable to the infamous hospital scene in the End of Evangelion for how anti-fanservice they are when the audience realizes they're depicting acts of (heavily censored) s*xual assault. Likewise, there's even more brutal violence, humanity gets swallowed by clothing, and the series gets washed out colors during the depressing timeskip.
9) Vinland Saga
A seinen anime focusing on a fictionalized historical telling set primarily in Europe shortly after Iceland's settlement, the seinen anime Vinland Saga details the fraught upbringing of Thorfinn, a young Icelandic boy whose father left behind a violent past as a viking. After his father Thor's death, Thorfinn's thirst for revenge saw him enlist in a monstrous band of mercenaries led by Askeladd, who killed his father.
The quest for revenge saw Thorfinn battle and bloody himself in his singular quest, enlisting in Askeladd's band to see him die for his actions. The only problem is that revenge never materialized, as Askeladd chose to feign madness and was killed by the future king of Wales Canute.
Thorfinn became inconsolable as a result. With his hot temper and his need for revenge gone, he tried attacking Canute but failed and was enslaved. After several years, plenty of nightmares and kind aid from friends and allies, he began to recover from his neverending depression and become a better man.
Thorfinn didn't forget Askeladd, nor the lessons he was too stubborn to listen to. He dedicated his life to a pacifistic existence after becoming free from slavery, vowing to never harm another human. It was a remarkable shift from the boy that started with nothing but a cold desire for bloodshed.
8) Code Geass
The seinen anime Code Geass is the story of Lelouch vi Britannia, a young exiled prince of the mighty Britannian Empire, trying to get revenge on his father, Emperor Charles, for the death of his mother. It escalates into getting Japan free from Britannian rule and collapsing the empire as it goes along.
It didn't get any lighter throughout the series, but the darkest plotline had to be the Special Administrative Zone Massacre. Long story short, the kindhearted Princess Euphemia li Britannia set out to create special zones throughout Japan so Japanese people could have their rights and privileges restored.
Though Lelouch was convinced of the plan, his Geass was unknowingly active and he lost the ability to deactivate it. He joked that he could get her to do anything he wanted, including killing the Japanese. Unfortunately, Euphemia couldn't resist and complied with the order. This act forever stained all involved.
Euphemia came to be known as the "Massacre Princess," Lelouch doubled his efforts against Britannia, Suzaku became cold and irrecoverably angry against Zero even after discovering Lelouch's true identity. Additionally, the shockwaves from this gruesome massacre led to Japan vs. Britannia's conflict becoming all-out warfare.
7) Fist of the North Star
Despite its reputation as a hotblooded adventure, the seinen anime Fist of the North Star is set in a Mad Max-esque post-apocalyptic wasteland and creates a truly unique world with its use of larger-than-life characters and focus on martial arts.
The Mad Max comparison is unavoidable, as the esthetic of the grungy biker looks, the villains looking as tall as buildings sometimes, and the general feeling of campy action never leaves the anime. The only thing is, the world itself isn't a good place to live and plenty of nightmarish villains lurk around every corner.
One of the darker plotlines involves a fighting style called Hokuto Ryuuken, or Big Dipper Shining Stone Fist, which turns the user demonic. A martial artist named Jukei used it to kill his wife, child, and others without ever remembering a thing about it. One of the practitioners of this style was a man named Kaioh.
Kaioh was worse than even the despot Raoh was, at least Raoh had something of a good intent to see the world shine brightly again. For a seinen anime, Kaioh came off as just plain evil: he killed his sister to drive a wedge between Kenshiro and Hyou, killed his pet dog, and reveled in the act of killing and violence.
6) Tokyo Ghoul
A departure from hotblooded into the more horrific genres, seinen anime Tokyo Ghoul centers around menacing beings known as ghouls, supernatural creatures who satisfy their thirst by feeding on humans. University freshman Ken Kaneki finds himself pulled into this murky underworld when he finds himself turned into a half-ghoul.
While that may sound like the recipe for a shonen anime, what makes Tokyo Ghoul a seinen anime is that it has a horror aspect that never truly leaves. It starts with Ken being nearly killed after his date turns out to be a ghoul, and just keeps getting more horrific from there.
The darkest, if not one, darker storyline comes into play when Kaneki confronts Dr. Ahikiro Kanou in the Raid of Kanou's Lab arc. In the seinen anime, Kanou was mentioned several times as having been the one to turn Kaneki into a ghoul. Kanou stated that he did so to create many half-ghouls and basically become a god to shine light and truth on the world.
His attempt to recruit Kaneki into the terroristic ghoul organization Aogiri Tree nearly worked, were it not for Renji Yomo battering in to rescue Rize. The 'good' Doctor Kanou made his leave by siccing his horrifying failed experiments on Kaneki, forcing him to consume these half-life ghouls to survive, nearly losing his mind in the process.
Hellsing would be mostly at the top were it not for the over-the-top awesomeness it exudes despite its dark subject matter as a seinen anime. The crux of the story involves the vampire Alucard and his bloody work for the Hellsing Organization, dedicated to eradicating the things that go bump in the night for Great Britain.
Now, this usually involves shooting, biting, burning, and all manner of gruesome and grotesque actions. Considering this is a seinen anime about vampires, it's expected. It also involves Nazi vampires, werewolves, and corrupt priests. It's almost like the authors were inspired by Castlevania when Hellsing was created.
The darkest of its plotlines? There are many to choose from. Seras being tortured by Zorin via maiming and having her eyes gouged out? The gruesome deaths of many of the villains, including Jan Valentine (burned alive), Rip Van Winkle (slowly shot and assimilated by Alucard), or any of the hapless mooks Alucard flays?
Well, this one goes to Hellsing Ultimate. Long story short, the Millennium organization blitzes London and begins mass slaughter until the Hellsing Organization and even the villainous Iscariot/Vatican Section XIII steps in to cease it! It culminates in the slaughter of millions, with Alucard having to sacrifice all three million of his souls to stop everything going on.
4) Drifting Net Café
So, what's worse or darker than a seinen anime involving mass slaughter via vampires with loads of blood spilling? How about being trapped in unreality in an internet cafe? That's the premise behind the seinen manga Drifting Net Cafe.
As a synopsis, 29-year-old Toki Kouichi is a hardworking husband with a major change looming: his wife is pregnant. Kouichi heads to a net café to pass some time before going back home and running into his middle school crush, Touno Kaho. As they rekindle their friendship, they soon realize they're not in Japan anymore.
Stuck in a net café in the middle of nowhere with some rather sketchy people, Kaho and Kouichi descend into despair as a return to the city they once knew seems less and less likely. This manga isn't exactly for the faint of heart, featuring borderline H material, s*xual assault, murder and manipulation.
It's a horrifying journey into the unknown as Kouichi and Kaho try to survive in the new world they've inexplicably found themselves in. It doesn't help that people begin to go missing, or that other patrons have ideas other than simply returning to the real world.
Berserk is already well known as a seinen anime/manga. The crux of this one is that Guts is a mercenary trying to find his way in a world that's rather bleak, from being born from his mother's corpse to his abusive father, to Griffith going evil, Guts endures a lot.
Though Berserk has that same spark of never surrendering to the dark as a shonen, this seinen anime has a lot of darkness. Everything from the previously mentioned birth of Guts, to Griffith turning evil could fit on this list. For the purposes of simplicity, however, this will focus on the Eclipse events.
In all of seinen anime Berserk, there’s nothing as nightmarish as the Eclipse. Here, Berserk subjected viewers to the torturous deaths of beloved characters like Corkus, Pippin, Judeau, and their comrades. What's worse was that Griffith sacrificed them for his dreams of power, and gained said power to become the 5th God Hand Femto.
He then proceeded to r*pe Casca in front of Guts. There was no going back between Guts and Griffith after this, as Guts hated his former friend forever and waged war against him and the cult that drove Griffith to the Eclipse. Casca required years of aid and a long journey to restore her mind, though she still suffered from extreme PTSD.
2) Oyasumi Punpun/Goodnight Punpun
So, it was a tossup between either this or the next entry on the list for the darkest plotline in Seinen anime and manga, they're both pretty horrifying. Goodnight Punpun is more depressing most assuredly, but seinen anime and manga writer Junji Ito has one over it.
The gist of the odd seinen manga Goodnight Punpun is that Punpun himself is a boy depicted as a bird character (his immediate family are likewise depicted as birds) who goes through absolute and total hell due to his abusive mother, ineffectual father, and his own issues and insecurties regarding his girlfriend Aiko.
The darkest turning point in an already dark manga has to be when Punpun and Aiko were on the run after killing Aiko's mother. It was a self-defense move to be sure, as Aiko's mother was about to kill her and managed to stab her, but still! It doesn't help that things spiraled out of control for the two of them afterward.
It's a sad tale that ends with the two of them running away together and Aiko unfortunately committing suicide when the two are older. Everything Punpun goes through nearly ends up with him doing the same. While he has people in his corner, and the story does end happier than it started off with, it's still a bleak story.
Again, it was a tossup between either seinen anime creator/mangaka Junji Ito's most famous work or Goodnight Punpun. But in the end, Uzumaki won out. Why? Uzumaki is the only seinen manga (the seinen anime is in production) on this list that definitely ends tragically and as a downer. This one is just another warning to turn back if you don't like depictions of body horror.
Uzumaki is a full cosmic horror story about a small Japanese town named Kurôzu-cho, and a girl named Kirie who notices some very unsual anomalies happening around it. Again, a warning for body horror.
To start, there's the twisting and cortortions into spirals where people die from being cortorted. People who slowly and sluggishly and in graphic detail turn into snails, with their bodies exuding slime and becoming softer. The vampire babies in the hospital serve blood-filled "mushrooms" to patients to feed their ever growing need for blood.
That's before we get to the fact that the town is caught in a time loop that Kirie and her boyfriend Shuichi are frozen in thanks to trying to stop it. The entire city is consumed into spirals, and the two unfortunately are as well. Their one bright spot is that they're together and they're not going to die, just going to become immobile for centuries.