Honestly, if you walked into Black Butler Book of Circus expecting the same whimsical, monster-of-the-week vibe from the first half of season one, you were probably in for a massive shock. It’s brutal. It is arguably the most faithful adaptation of Yana Toboso’s manga, specifically covering the Noah’s Ark Circus arc. This isn't just another gothic mystery. It’s a total deconstruction of Ciel Phantomhive’s morality.
People often forget how weird the anime's timeline got. After the first season went off the rails with original content and the second season introduced the (highly divisive) Alois Trancy, fans were confused. Then came 2014. A-1 Pictures decided to ignore the non-canon filler and jump straight back into the manga's timeline. It was the right call.
The story kicks off with Ciel and his demon butler, Sebastian Michaelis, investigating a string of missing children. The trail leads them to a traveling circus. On the surface, it’s all glitter and cheers. But underneath? It’s a nightmare fueled by Victorian-era class disparity and a very literal sense of "selling your soul."
The Noah’s Ark Circus: Not Your Average Villains
What makes Black Butler Book of Circus so gripping is that the "villains" aren't traditional monsters. Joker, Beast, Dagger, and the rest of the troupe are orphans who grew up in the East End gutters. They didn't join the circus to be evil. They did it to survive. They were rescued by a mysterious "Father" figure who gave them prosthetic limbs and a home.
The tragedy is deep. You see them as a family. Joker, voiced with a strained cheerfulness by Mamoru Miyano, is someone you almost want to root for until you realize what he’s actually doing to keep his siblings safe. They are kidnappers. They are murderers. Yet, Toboso writes them with such empathy that when Ciel finally makes his move, it doesn’t feel like a victory. It feels like a slaughter.
I remember watching the scene where Ciel and Sebastian "audition" for the circus under the aliases Smile and Black. It starts off almost like a comedy. Sebastian, a literal demon from hell, struggling to deal with a tiger biting his head is peak Black Butler humor. But the tone shifts so fast. One minute you’re laughing at Ciel failing at acrobatics, and the next, you’re staring at the horrific medical experiments happening behind the scenes.
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Why the "Book of Circus" Animation Style Mattered
The aesthetic changed. It had to. The vibrant colors of the circus tents contrast sharply with the muted, foggy streets of London. A-1 Pictures leaned heavily into the "Kuroshitsuji" gothic roots here. The character designs for the circus members are elaborate—Beast’s leather-and-lace outfit or Joker’s pierrot makeup—which makes their eventual downfall even more visceral.
There’s a specific focus on the prosthetic limbs. In the Victorian era, losing a limb meant a life of begging. The "Father" figure, Baron Kelvin, exploited this desperation. He didn't just give them limbs; he gave them a purpose, even if that purpose was horrific. The animation doesn't shy away from the grime. It’s dirty. It’s uncomfortable. It’s perfect.
The Baron Kelvin Problem
Let’s talk about Kelvin. He is one of the most repulsive characters in the entire series. Most villains in Black Butler have some shred of coolness or a tragic backstory that makes them "stannable." Not Kelvin. He is a representation of the worst kind of obsession. His obsession with the Phantomhive family and the "beauty" of the tragic events that befell Ciel is stomach-turning.
His manor is a house of horrors. When Ciel finally enters that basement, the show stops being an action-shonen and becomes a psychological horror. The revelation of what the "prosthetics" are actually made of? That’s the moment most viewers realize this isn't a show for kids. It’s a commentary on how the elite consume the poor—literally.
Sebastian and Ciel: A Dynamic Shift
In Black Butler Book of Circus, we see Sebastian at his most predatory. There’s a scene with Beast that still causes debates in the fandom. It’s the "seduction" scene. Sebastian uses his demonic charm to extract information, and it’s a stark reminder that he is not Ciel’s friend. He is a predator playing a role. He doesn't have a moral compass; he has an appetite.
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Ciel, on the other hand, hits a breaking point. We see his asthma return—a physical manifestation of his trauma triggered by the similarities between Kelvin’s basement and the cult that tortured him.
But Ciel isn't a hero.
The ending of this arc is what cements the series as a masterpiece of dark fantasy. Most protagonists would save the remaining children. Ciel doesn't. He orders the manor burned to the ground with everyone inside. It's cold. It's calculated. It's exactly what a Queen’s Watchdog would do. When he laughs at the end, it’s not a laugh of joy. It’s a laugh of someone who has realized that the world is irredeemably broken.
The Music of the Macabre
You can't discuss this season without mentioning "Enamel" by SID. It might be the best opening theme the series ever had. It’s frantic, jagged, and perfectly captures the feeling of a circus spinning out of control. Then you have the ending theme, "Aoki Tsuki Michite" by Akira, which provides a somber, melancholic comedown after the intensity of each episode.
The soundtrack by Yasunori Mitsuda—who worked on Chrono Trigger and Xenogears—is haunting. He uses accordions and violins to create that "creepy carnival" atmosphere that lingers in your head long after the credits roll. It’s a masterclass in atmospheric world-building.
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Misconceptions About the Timeline
A lot of people ask: "Do I need to watch Season 2 before Book of Circus?"
Short answer: No.
Long answer: Absolutely not. In fact, it might be better if you don't. Black Butler Book of Circus follows the manga after the Curry Contest arc (which ends around episode 15 of Season 1). If you try to fit it into the Season 2 continuity, nothing makes sense because Season 2 had a completely different ending for Ciel and Sebastian. Think of "Book of Circus" as a soft reboot that puts the train back on the tracks.
The Legacy of Noah's Ark
This arc changed how we view Ciel. Before this, you could argue he was just a bratty kid with a cool bodyguard. After the circus, you realize he’s a victim who became a perpetrator. The tragedy of the circus performers is that they were looking for a home and found a monster. The tragedy of Ciel is that he looked for revenge and lost his humanity.
It’s a bleak story. There are no winners. Even the "orphans" the circus performers were trying to protect at their original home turned out to be long gone. Every sacrifice made by Joker and his team was for nothing. It’s a gut-punch of an ending that stays with you.
If you're looking for a series that explores the dark underbelly of Victorian society while maintaining a high-stakes supernatural mystery, this is it. It’s the peak of the franchise. It’s the moment the series stopped being about a "cool butler" and started being about the cost of vengeance.
Actionable Insights for Fans and New Viewers
- Watch Order: Skip the second half of Season 1 and all of Season 2 if you want the "true" story. Move from the Curry Contest arc directly into Black Butler Book of Circus, followed by the "Book of Murder" OVAs and the "Book of the Atlantic" movie.
- Manga Context: Read volumes 6 through 9 of the manga for the original source material. Yana Toboso’s art in these chapters is incredibly detailed, especially regarding the circus costumes and the architectural details of the Kelvin manor.
- Character Study: Pay attention to Doll’s relationship with Ciel. Her betrayal and his subsequent reaction are the emotional core of the finale. It’s the clearest indicator of Ciel’s character arc in the entire series.
- Theatrical Themes: Notice the recurring use of stage metaphors. The circus isn't just a setting; it's a commentary on how all the characters—including Sebastian—are performing roles for an audience that doesn't care if they live or die.
The world of the Noah’s Ark Circus is one of illusions and harsh realities. It’s a reminder that sometimes, the monsters aren't the ones with the fangs, but the ones holding the contracts.