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Secre Swallowtail/Nero

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Cool Beauty

^{Click here to see her as an anti-bird}

Voiced by: Hitomi Sasaki (Japanese, bird form), Ayane Sakura (Japanese, human form), Monica Rial (English)

Debut: Chapter 2 (Manga), Episode 3 (Anime)

Magic Attribute: Sealing

"The ones you looked down on and stepped on and toyed with are going to defeat you today!!"

An anti-bird that has taken a liking to Asta. In truth, she's the bird form of Secre Swallowtail. A servant of the first Wizard King, Lumiere Silvamillion Clover, she helped develop the magic tools he worked on to achieve his dream of equality within the kingdom. On the day of the elf massacre, Secre saved Lumiere using Forbidden Magic, at the cost of spending centuries as a bird. She later joins the Black Bulls.

She uses Sealing Magic, an ancient magic that has been affected by her use of Forbidden Magic, allowing her to seal and unseal objects, individuals, and even damage.

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# — G

Adaptation Dye-Job: The anime turns her black hair in her human form dark blue.
Alliterative Name: Her true name, Secre Swallowtail. Funnily enough, Noelle's suggestion for her name was also alliterative and began with an S, Silvantus Schnauzer.
Aloof Dark-Haired Girl: Black hair in her human form that's given a bluer shade in the anime, described as a cool beauty by Finral, and generally very calm and apathetic.
Animal Motifs: Unsurprisingly, swallows. She can transform into an anti-bird which resembles a real-life swallow, her true surname is "Swallowtail", and her black dress is feathered:
- In Christianity, swallows are symbols of sacrifice, rebirth, and new beginnings, fitting with how she turned into a bird for five centuries as the cost of saving Lumiere's life and sealing Zagred, along with finding new purpose in life in the Black Bulls and renaming herself as Nero following Lumiere's death.
- Swallows are also associated with fertility and maternity, tying in to how she acts as something of a guardian angel to Asta and is later revealed to have saved the life of the pregnant Tetia and one of her unborn children, who would become the ancestor of the elves in Elysia.
Anime Hair: Even before becoming an anti-bird, Secre had her large pair of bird-like hair extensions protruding from the top of her head. Considering her family name, it's all the more fitting.
Animorphism: After unsealing Lumiere, she can switch between her anti-bird form and human form at will.
Apathetic Pet: She's a magic-hating bird who becomes Asta's Head Pet after taking a liking to his complete lack of magical power. Despite this, she constantly pecks at Asta's head, never shows him any real affection, and is generally disinterested in most affairs until he's actually needed. It's later revealed that she's not only a human, but has also gained a loyalty to and admiration for Asta after witnessing him overcome many obstacles throughout his journey.
Ascended Extra: She goes from being Asta's bird companion to a major supporting character after The Reveal that she's actually a former servant of the first Wizard King who has been preparing against Zagred, becoming secondary in relevance only to Asta, Yuno, and Noelle.
Badass Adorable: She has a cute appearance in her human form and can turn into an adorable anti-bird, while still being a competent mage with a very unique magic that makes her a great support mage.
Barefoot Loon: While not wacky, her evident trauma has left her a bit off, as seen in her perpetually gloomy and detached nature, and goes barefoot in her base human form as a further sign of it. Subverted later, as she adopts simple shoes shortly before joining the Black Bulls.
Beauty Equals Goodness: Described as very cute by Noelle and called a cool beauty by Finral, and very firmly on the side of good.
Because You Were Nice to Me:
- Secre's devotion to Lumiere comes from him being the first person to acknowledge her potential, with Secre having been seen as useless all her life for her magic. Understandably based on her backstory, she also sympathized with Lumiere's goals, inventing magic items so people who'd been unfortunate regarding their magic would be able to use different types of spells and society could be more equal.
- The Black Bulls' refusal to abandon her to the Magic Parliament, even despite her insistence that she had been using them all this time to complete her mission, touches Nero enough to unseal her handcuffs and formally join the squad.
Becoming the Mask:
- She admits to originally wanting to use Asta as a tool for her own goals. After helping him again and again while pretending to be his loyal yet irritable Head Pet, she becomes genuinely fond of him and helps him simply because she wants to see him reach his dream.
- Nero tells the Black Bulls that she used them for her mission to save them from the wrath of the Magic Parliament, showing that she did grow to care for them. Yami tells Nero that she can't say that after spending so much time with them, with the others inviting her to join the squad, not caring about her no longer being human. She's touched and officially joins the Black Bulls.
Beware the Quiet Ones: The reserved, distant girl who can transform into a bird to be inconspicuous has used Forbidden Magic, with the aftereffect of making her magic powerful enough to seal a powerful devil for five centuries and shown a high level of planning in preparing for said devil's inevitable return, with Nero ultimately being very vital to Zagred's defeat.
Big Damn Heroes: Thanks to being inconspicuous and able to fly as an anti-bird, Nero does this often after regaining her human form:
- She comes right after Yami bisects Zagred to seal Asta's damage, letting him enter his Black Asta form again to kill the devil.
- Nero dives as a bird into Undine's water, transforming into her human form to unseal Asta from his shackles.
- She does this again as part of Lolopechka's plan, going in to seal Vanica after she uses 70% of Megicula's power. It almost works had it not been for Megicula's Curse-Warding Magic, which weakens spell arrays against it.
Big Good: It turns out that she knew everything involving the first Wizard King and his battle with Licht-turned-demon that set the entire series into motion, and has been setting the right conditions in mind for handling the inevitable consequences involved for five hundred years. As a result of Asta inheriting Licht's five-leaf clover grimoire by pure chance, she thus became his guardian of sorts.
Blonde, Brunette, Redhead:
- Of the girls who accompany Asta to the Heart Kingdom, Nero is the Brunette to Noelle's Blonde and Mimosa's Redhead.
- Lolopechka becomes the Brunette after they befriend her during the six month time skip, with Nero usually in her bird form.
Blue Blood: Secre was the daughter of a noble family, but was assigned to be a royal servant to Lumiere for having a seemingly useless magic.
Boring, but Practical: Sealing Magic is by no means flashy visually especially compared to the powerful mages in the story and has little combat ability. But it makes up for it by giving Nero a variety of techniques — closing wounds, sealing damage, freeing allies, and imprisoning enemies.
Breakout Character: She became loved by many fans for her cute design as both a bird and a human, quiet yet kind personality, important role in the first saga, and interesting magic. She ranked 6th in the fourth popularity poll and became a major supporting character after The Reveal that she's a human, with her voice actress billed alongside the voice actors of Asta, Yuno, Noelle, and Yami, and Nero featured with Noelle in promotional art by Tabata for the series◊.
Broken Bird: Quite literally, but in her past Nero was treated badly for her seemingly useless magic and went from being a noblewoman to a royal servant. She then witnessed Zagred use her and Lumiere's invention to massacre the elves and then had to seal her beloved prince as a statue at the cost of turning into a bird for 500 years. In the present day, she's generally gloomy and quiet, but sometimes shows a more emotional, cheerful side around Asta and the other Black Bulls.
Brooding Boy, Gentle Girl: Gender inverted, with Secre being the distanced, stoic Brooding Girl to Lumiere's nice, idealistic Gentle Boy. She was assigned to be his servant, thinking he would be arrogant like the other royalty, but he turned out to be very kind to her surprise. Lumiere's recognition of her magical potential, combined with his goal of equality, inspired Secre's deep loyalty to him.
The Cavalry: She and the rest of the forces who were training in Elysia join up with the Magic Knights and Resistance in the Spade Kingdom to help them fight against the devils released from the underworld and the Dark Triad.
Character Tics: As a bird, Nero often repeatedly pecks at Asta when she's annoyed at or trying to convey something to him. In her human form, Nero does this by pinching his cheek.
The Chessmaster: Chose to follow Asta after he was chosen by the five-leaf grimoire and, as a bird, guided the Black Bulls to obtain the magic stones all in preparation for Zagred's return, using them to unseal Lumiere and Licht's soul after centuries and playing a part in Zagred's defeat. She calls herself out for this to the Black Bulls when they try to save her from the Magic Parliament, but Yami retorts that the squad has spent too much time with Nero for them to abandon her.
Color Motif: Black. She has black hair (blue in the anime), wears a black dress, can transform into a black anti-bird, joins the Black Bulls, and her given name "Nero" means "black" in Italian. She also used Forbidden Magic, giving her wegs that mark her as a servant of the devil to the Magic Parliament, and, after contemplating joining Lumiere in the afterlife as he dies, finds companionship in the Black Bulls.
Combat Pragmatist: Downplayed, but thanks to her Sealing Magic having little offensive power and based more on its ability to free allies from bindings and seal enemies, Nero is very reliant on the element of surprise through using her anti-bird form.
Combination Attack: With Zora, using Secret Counter Trap Magic x Mana Method: Sealing Magic to save Asta from Lucifero's punch by having Zora take the punch and hold out for a short time with the power of their magics.
The Comically Serious: Many funny moments involving Nero revolve around her completely maintaining her emotionless and deadpan demeanor, such as when Finral asks her out for a date, she pinches at Asta's cheeks for aspiring to be like Lumiere, and even her serious expression as a bird around the hilarity of others. Best seen when her and Asta are tricked to being put on trial for the elf reincarnation:
Asta: HEEEEEEEEEEEEY!! WHAT THE HECK IS THIS?!!
Nero: ...
Creepy Shadowed Undereyes: One of the many after-effects of overusing Forbidden Magic and turning into an anti-bird, Nero gained dark circles underneath her eyes which, combined with Exhausted Eye Bags, gave her a gloomy, hostile aura.
Cursed with Awesome: Using the magic stones to gain the power of Forbidden Magic made her no longer human and turned her into a bird for five centuries but also permanently strengthened her Sealing Magic, letting Nero seal enemies in cubical prisons strong enough to trap Zagred for nearly that entire time. It's for this reason that she's classified as an Arcane Stage who, according to Lolopechka, have the potential to defeat devils. Thanks to this Nero is also now able to freely switch between her bird and human forms using her magic, giving her the element of surprise in combat.
Cute Monster Girl: Due to overusing Forbidden Magic, Nero is no longer fully human. Despite this, the only change to her appearance was gaining horns, and she is noted to be very cute in her true form by both Finral and Noelle.
Dangerous Forbidden Technique: Secre used Forbidden Magic powered by the magic stones to seal Zagred for centuries, which gave her her horns. She then used the stones again to seal Lumiere to save his life and unseal him in the future, which caused her to stay a bird for 500 years.
Dare to Be Badass: She does this to Asta after unsealing his damage, allowing him to draw out his anti-magic power and defeat Zagred.
"You're going to be the Wizard King, aren't you?!!"
Dark Is Not Evil: Nero has red eyes, horns from using Forbidden Magic, and wears a black dress. She's also vital to stopping Zagred and becomes Asta's loyal companion.
Deadpan Snarker: Nero tends to calmly and bluntly put down others, especially Asta.
Defrosting Ice Queen: After joining the Black Bulls, Nero is slowly warming up and becoming more expressive of her emotions.
Determinator: Spent five-hundred years as a bird, biding her time and watching over the Clover Kingdom to prepare against the eventual return of Zagred to save the kingdom from his scheme. As Magna puts it, she's "totally the man".
The Dog Was the Mastermind: Inverted. Nero, the bird who becomes Asta's pet, is in truth a servant of the first Wizard King from five centuries ago who knew all along about the circumstances of the conflict with the elves. She had been collecting the magic stones to prepare against the consequences of the massacre as well as Zagred's return. She chose to accompany Asta because he was chosen by Licht's former grimoire, but grew to care for him and the rest of the Black Bulls throughout the story.
Driven to Suicide: Downplayed. As Lumiere's body crumbles away after the battle with Zagred, Nero states that she'll go with him. Lumiere tells her that he doesn't want her to close off her potential, and asks her to watch the futures and ideals of the present-day Magic Knights to play out.
Dull Eyes of Unhappiness: After five hundred years of being an anti-bird, not to mention the traumatizing circumstances she's been through, she sports these. They do brighten up during more emotional moments, though.
Early-Bird Cameo: Literally. Nero can be seen on top of Asta's head in Chapter 2, distinguished from the other anti-birds by her unique appearance, before she reveals that she had been hiding in Asta's clothes since then in Chapter 9.
Eerie Pale-Skinned Brunette: She has black hair with a blue tint and red eyes. Combined with her horns, they mark her as no longer fully human.
Emotionless Girl: Nero is almost always calm and apathetic, rarely emoting and contrasting her with the more expressive Asta. It's understandable due to her past trauma, but she does show emotions occasionally around the Black Bulls after formally joining them as well as during more serious moments.
Energetic and Soft-Spoken Duo: Nero is the aloof, calm Soft-Spoken to Asta's boisterous, cheerful Energetic. Despite their differences in temperament, Nero is very loyal to Asta after spending time with him throughout his journey, helping as a dutiful companion.
Exhausted Eye Bags: Has these after regaining her human form, though they tend to go away or at least be more akin to a natural eyeliner in more emotional moments.
Fairytale Motifs: Secre and Prince Lumiere are based on the swallow and prince from The Happy Prince. Secre turned Lumiere into a statue with the magic stones to save his life, at the cost of turning into a bird for five centuries. Here, however, she gives the statue of Lumiere the magic stones to unseal him in order to defeat Zagred. And despite her pleas, he lets her go to live out the rest of her life as he crumbles away.
Fan of Underdog: After spending time with Asta and seeing his accomplishments throughout the story, she believes he can achieve his dream of becoming the Wizard King, telling him this as motivation for him to land the killing blow on Zagred.
Fanservice with a Smile: She acts as a waitress, dressed up in the expected outfit, in Episode 135.
Feel No Pain: Her Sealing Magic seal wounds and pain without actually healing, letting Asta re-enter his Black form during the battle against the Word Devil. During the Black Bulls' battle against Damnatio her magic helps them buy time for Asta to come through the Door of Fate in spite of their wounds.
Fighter, Mage, Thief: In their strategy against Vanica, Noelle, the one actually battling Vanica with her lance and attack spells, is the Fighter; Lolopechka, increasing the power of Noelle's Water Magic with her Ludic Sanctuary, is the Mage; Nero, inconspicuous as a bird to fly in and seal Vanica after she uses all of Megicula's devil power, is the Thief. Their strategy falls apart with Megicula's Curse-Warding Magic weakening rune arrays, breaking out of Nero's prison and destroying Lolopechka's Ludic Sanctuary.
Foil: With Noelle. Noelle wears a white feathered jacket while Nero is in a black feathered dress. Noelle is a powerful attack mage; Nero's magic has little combat use so she serves more as a support mage. Noelle's bad magic control left her with only the option of joining the Black Bulls in spite of being a royal. Nero was born a noblewoman, but became a royal servant because of her seemingly useless sealing magic. Noelle's family's sigil is eagles and Nero on the other hand is associated with the swallow. Nero's use of forbidden magic permanently affected her sealing magic and gave her wegs, which are considered cursed and lead her to be accused as devil-possessed. In contrast, Noelle is associated with holiness upon becoming a Saint Stage complete with a Holy Halo, gaining the power to purify devils and destroy malice.
Forced Transformation: Using Forbidden Magic turned Secre into an anti-bird for 500 years, unable to use her Sealing Magic and speak. Only after the Shadow Palace appears is she able to speak again, and when Lumiere is unsealed using the magic stones she's able to return to her human form and use her magic.
Fragile Speedster: Nero isn't an attack mage, but can use her bird form to fly at great speed and use the element of surprise to perform a variety of important actions in battle like free allies from bindings, seal damage and wounds, and trap enemies in a powerful prison.
The Gadfly:
- She really likes to peck at Asta as a bird. And even as a human, Nero tends to pinch at his cheeks and make condescending remarks at him, sometimes with a smile on her face.
- At Asta's promotional ceremony she tells Noelle and Mimosa that Asta plans on confessing his love, turning the girls flustered while thinking "This is entertaining" with a blank expression.
Gender-Blender Name: "Nero" is a traditionally Roman male name, and she continues to go by this even after her true gender is revealed.
Godzilla Threshold: She used the elves' magic stones, only usable by the elves without severe consequences, to cast Forbidden Magic, gaining the power needed to seal Lumiere as a statue so that he could survive his wounds from fighting a transformed Licht and seal Zagred. This came at the cost of turning Nero into an anti-bird for 500 years and left her no longer fully human.
Goth Girls Know Magic: Nero has the goth part down with her dark hair, black dress, emotionless demeanor, and occasional snark. She also uses an ancient magic, Sealing Magic, affected by her use of Forbidden Magic over five centuries ago, making her an Arcane Stage whose magical powers are unconventional.
Graceful Ladies Like Purple: The general demeanor of Secre, who was born a noblewoman, is reserved and graceful, and in the past as Lumiere's servant she had worn a purple dress.

H — R

Hair Color Dissonance: Her hair is colored black in the manga, but is dark blue in the color page for the popularity poll in Chapter 211. The anime opts to make her hair dark blue.
Has a Type: According to the Volume 31 Questions Brigade, she likes someone who's very studious.
Head Pet: Nero acts as such for Asta. She makes herself useful by acting as a magic compass of sorts, able to detect sources of ambient magical power. Asta finds her useful, but doesn't enjoy her presence that much as she often pecks at him for attention. She also helps Asta find the other anti-magic sword amongst the treasures when Mars manages to overpower him.
Heal the Cutie: Secre was disowned by her noble family and left to become a royal servant due to her seemingly useless magic, which she herself came to believe to be vulgar and led her to have a sullen, quiet demeanor. Then she met Lumiere, who acknowledged her worth and helped her achieve the true potential of her magic. But sadly the elves are all killed by Zagred and Lumiere is on the verge of death after defeating a transformed Licht. To save the kingdom and the prince, Secre uses Forbidden Magic to seal Zagred and Lumiere as a statue, turning her into a bird for five centuries. After she regains the ability to speak, she unseals Lumiere and helps the Magic Knights defeat Zagred, with Lumiere dying shortly after to her heartbreak, with Secre even proposing that she go with him to the afterlife. But at the Magic Parliament trial, the Black Bulls refuse to abandon her in spite of her using them for her mission and being no longer human and from a different era. Touched and recalling Lumiere's last words for her to achieve her true potential and live on, Secre officially joins the squad and is welcomed by them.
Heart Is an Awesome Power: Originally, she thought that her Sealing Magic could only be used to open and close objects. After spending time with Lumiere, she unlocked her true potential, and can use it to seal magic into objects, wounds, and body damage. Using it with Forbidden Magic allowed her to seal Zagred for centuries.
Her Heart Will Go On: When the body of Lumiere is about to crumble away after the battle against Zagred, Nero tells him that she'll go with him. Lumiere asks her not to, telling Nero that she should move on and not close off her potential by dying with him because she has so much left to accomplish with her life. Nero finds companionship without him in the Black Bulls, remembering Lumiere's words when they save her and Asta from the Magic Parliament.
Heroic Sacrifice: As Secre, she sealed away Zagred, the devil that caused the entire series' plot, but the forbidden power needed to pull that feat off resulted in losing her human form and becoming an anti-bird with no latent magic left over. Ultimately, it turns out this helped her fly under the radar of the entire cast as a result.
Hero with Bad Publicity: Nero, along with Asta, becomes a pariah for her involvement in the elves' attack on the Clover Kingdom because of her wegs, seen as marks that she's a servant of the devil, from using Forbidden Magic five centuries ago to seal Zagred and Lumiere. Julius bails her out by telling her to investigate the devils together with the Black Bulls.
History Repeats: Secre was a loyal servant of the first Wizard King, who dreamed of establishing equality within the socially stratified Clover Kingdom. Five centuries later, she becomes loyal to Asta, a young Magic Knight who aspires to become the Wizard King and shares Lumiere's goal of equality, with Secre wholeheartedly believing that he can achieve his dream. She sees Lumiere in Asta when he comes to save the Black Bulls from a Paladin Damnatio.
Horned Humanoid: As an after effect of using Forbidden Magic, she gained two wegs on her head.
Humanizing Tears: Usually frowning and stoic, but she shows a softer expression◊ when crying, which makes her sad moments stand out even moreso.
Idiot Hair: She has two locks of hair sticking up in both her bird and human forms.
Implied Love Interest: To Lumiere. Secre refers to him as "my prince" and he was the first one to acknowledge her potential. As a result, she was very devoted to him, using Forbidden Magic to keep him alive at the cost of being turned into a bird for 500 years and willing to follow him to the afterlife after the battle with Zagred. However, it never is confirmed whether or not their relationship was romantic and he dies shortly after he's unsealed.
Inconsistent Spelling: Downplayed. Viz first romanizes her name as "Secré" but later changes it to just "Secre".
Indifferent Beauty: Didn't so much as react when Finral complimented her looks and tried to ask her out. Given that they were in the midst of an invasion by the elves, it's understandable.
Intelligible Unintelligible: When Secre is in her Nero form, she communicates through bird noises, but Asta and other mages can understand her. After regaining her human form, she can now speak in her bird form.
Ironic Name: A quiet, kind servant of the first Wizard King who wished to help him achieve peace between humans and elves has the same name as the roman emperor Nero, who's infamous for his cruelty, tyranny, and persecution of early Christians.
It's Personal: She has her own personal motive to defeat Vanica who cursed Lolopechka, who she becomes close to during the six month time skip, to die.
Kimono Fanservice: Along with the other females of the Black Bulls, she's dressed up in a kimono on the colored cover of Chapter 277.
Like Brother and Sister: Asta and Nero have this relationship. As a bird, she'll repeatedly peck at Asta and pull his hair to his annoyance. Despite this, the two deeply care for each other. Through spending time with Asta, she grows to have a strong sense of loyalty to him and genuinely believes that he can achieve his dream of becoming the Wizard King.
Little Black Dress: Her outfit in her human form is a short, black feathered dress, fitting with both her bird form and being a "cool beauty" as stated by Finral.
Loner-Turned-Friend: Very aloof and originally used the Black Bulls for her mission. However, over time she gained a deep admiration and loyalty to Asta because of his unwavering determination and feats, and the Black Bulls refuse to abandon her to the Magic Parliament when she tells them to leave without her, touching Nero with her officially joining the squad. She thinks about how they saved her and helped her regain her heart as they're attacked by Damnatio, pleading for Asta to come.
MacGuffin Guardian: After awakening as a bird years after she sealed Lumiere, Secre watched over the five-leaf clover grimoire that was formerly Licht's. When it chooses Asta, she accompanies him as a pet to continue overseeing it.
Mark of the Beast: Her wegs are an aftereffect of her use of Forbidden Magic to seal Zagred and Lumiere, which causes her to be accused as devil-possessed and a perpetrator of the elves' reincarnation by the Magic Parliament.
Meaningful Name:
- Luck names her Nero, since it means "black" in Italian. Not coincidentally (along with Julius and Augustus), it's also the name of a famous Roman emperor.
- Her real first name, "Secre", is Ukrainian for "secret", referring to how she was actually not only originally a human, but also a servant of the first Wizard King with ties to the elf massacre who has been preparing against Zagred's return the entire time.
- Her real last name is "Swallowtail" like the swallow bird family, fitting for how she can transform into a swallow-like anti-bird.
Meaningful Rename: Although she was originally known as Secre, after Lumiere passes away and she officially joins the Black Bulls, the others continue to address her as Nero.
The Medic: Nero's Sealing Magic has little offensive ability that ranks her only a Stage Six in that regard, used in battle to seal enemies and free allies from bindings. However, her magic can be used as Recovery Magic, allowing her to seal physical damage, letting Asta re-enter his Black form and even wounds and pain.
Minidress of Power: She wears a short black dress as a human, and although her magic doesn't have much offensive ability she's still an important member of the Black Bulls with her powerful Sealing Magic.
Morphic Resonance: In both her human and bird forms, she has her horns and slanted eyes. Even her black dress in her human form resembles feathers.
Ms. Fanservice: Downplayed compared to Vanessa, but she wears a black minidress and Finral finds her attractive. Not to mention the anime adds scenes of her dressed in a swimsuit and waitress uniform simply for fanservice.
Named After Somebody Famous: Her name as an anti-bird comes from the Roman emperor Nero, fitting with the Theme Naming of Julius and King Augustus Kira Clover to parallel the Clover Kingdom's conflict against the elves with the Roman Empire's against the Jews.
No Good Deed Goes Unpunished: Despite spending 500 years as as anti-bird, preparing against Zagred's return and playing an important part in the devil's defeat, Nero as well as Asta are both framed as scapegoats for the elves' reincarnation by Damnatio because of their wegs, seen by the Magic Parliament as signs that they're servants of the devil. Luckily, the Black Bulls save them and they're stopped from being executed by Julius, who orders the Black Bulls to investigate the devils in exile.
Non-Human Sidekick: As Nero, she acts as a chirping Head Pet to Asta after befriending him early on in the series. She can return to her bird form at will to ride on Asta's head for convenience's sake.
The Not-Love Interest: Nero is revealed to have been watching over Asta all this time as an anti-bird, is actually a cute human female, and, despite her annoyance at Asta's stupidity at times, deeply cares for him and has faith that he will achieve his dream, with the two having a close but platonic relationship.
Not So Stoic:
- She cries as Lumiere's body crumbles away after they defeat Zagred.
- Nero passionately proclaims that she's going to seal Vanica's devil power to save Lolopechka when using her magic empowered with runes on her.
- Nero cries when she learns that Tetia managed to survive after she sealed her wound, not knowing what had happened to her as she awakened as a bird years later after she sealed Lumiere.
Odd Friendship: She becomes Asta's loyal comrade and one of his closest companions, despite being a cold and quiet girl while Asta is very cheerful and outgoing.
Older Than They Look: She's physically 17, but spent 500 years as a bird.
Old Magic: Nero's Sealing Magic is classified as an Ancient Magic, what with her being over five-hundred years old and her magic's attribute involving an action, unlike most other mages in the story who have power of an elemental attribute. Combined with the fact that her magic was affected by using Forbidden Magic, she's a unique Arcane Stage mage.
Only Six Faces: Averted. In contrast to the other anti-birds in the series who all have the same appearance, as an anti-bird Nero is distinguished from them by her eyes, arrow-like tails, and horns.
Perpetual Frowner: Save for a couple of emotional moments, Nero is a major frowner and perpetually stoic even before her Dark and Troubled Past.
Personality Powers: Really fitting that an emotionally closed-off girl can seal and lock objects.
Personal Seals: A variation. Nero's unique grimoire, unlike others' grimoires which are all different for each person, has a wax seal for the three-leaf clover on the cover fitting with her ancient, rare sealing magic.
Power at a Price: Used the elven magic stones, not normally usable by humans, to gain the power from Forbidden Magic needed to seal Zagred as well as Lumiere as a statue, saving his life, at the cost of Secre turning into an anti-bird for five-hundred years, unable to return back into her human form until she used the magic stones to unseal Lumiere.
The Quiet One: Understandably due to the trauma of her past and spending centuries as a bird, she speaks little, which is more apparent when contrasted with the other Black Bulls and especially Asta.
Raven Hair, Ivory Skin: She has very pale skin and blue-tinted black hair. Noelle notes that she's adorable even in her human form, and Finral refers to her as a "cool beauty".
Really 700 Years Old: She's actually over 500 years old and was the close companion of the first Wizard King. Physically, she's 17 years old due to her curse.
Red Eyes, Take Warning: She has red eyes and although she isn't evil, combined with her horns from using Forbidden Magic, it adds to her eerie look.
Red Oni, Blue Oni: Asta is the Red Oni to Nero's Blue Oni; the hyperactive and energetic Asta in comparison with the aloof and collected Nero.
Rei Ayanami Expy: In her human form, Nero has bobbed hair that's dark blue in the anime, pale skin, red eyes, and a calm, emotionless demeanor. It's revealed that she's a loyal servant of the first Wizard King, and for 500 years she has been trapped in an anti-bird form and watching over Asta's grimoire all this time. She's also no longer human after using Forbidden Magic.
Riches to Rags: She was the born the daughter of a noble family, but because of her seemingly useless magic, she was relegated to being a royal servant.
Runic Magic: After training in the Heart Kingdom, she learns to use spell arrays, increasing the power of her Sealing Magic.

S — Z

Samus Is a Girl: Nero was believed to be male at first. She's revealed to be not only female but also originally a human.
Sarcastic Devotee: After spending time with Asta throughout his journey as an anti-bird to keep watch over his grimoire, Nero has become very loyal to him and genuinely believes that he will achieve his dream of becoming the Wizard King. This doesn't stop Nero from snarking at him as a bird or a human, repeatedly pecking at him or mocking his idiocy.
The Scapegoat: Her and Asta become this for the Magic Parliament, with Damnatio blaming her for the elves' possession of the Magic Knights because she's used Forbidden Magic. They manage to get out of it with the Magic Knights having the Black Bulls investigate the devils.
Semantic Superpower: Her Sealing Magic first seemed to only seal objects, unlocking and locking them. However, after working with Lumiere and having her magic affected by Forbidden Magic, she can use it to seal magic into tools, enemies in a cubical prison, damage, and wounds. She even changes between her anti-bird and human forms by sealing and unsealing herself.
Series Mascot: Thanks to her cute appearance as an anti-bird, Nero is this for the series.
Shapeshifter Mode Lock: Was stuck in the form of an anti-bird after overusing Forbidden Magic through the magic stones to save Lumiere's life. After she unseals him 500 years later, Nero can easily switch between her bird and human forms through her Sealing Magic.
Ship Tease: It's heavily implied that she's in love with the first Wizard King Lumiere. Unfortunately, he dies for real before anything can be said about it.
Shut Up, Hannibal!: Tells Zagred to be quiet when he calls her magic stunted and worthless now that he has his body after she had sealed him for centuries, proclaiming that the people he had looked down on and toyed with will defeat him today. It comes true when Secre uses her Sealing Magic to seal Asta's physical damage, letting him re-enter his Black form to land the killing blow on the devil.
Significant Wardrobe Shift: Secre is seen wearing a purple dress 500 years ago as Lumiere's servant. After returning to her human form in the present day, she wears the black dress Lumiere made for her which she continues wearing after his death, now named Nero and having decided to live on without him and with companionship in the Black Bulls.
Silk Hiding Steel: A reserved, petite young woman who wears a black dress. She's incredibly loyal to Lumiere and later Asta along with the other Black Bulls, with the emotional strength to spend five centuries as a bird to carry out her mission while having a unique ancient magic that makes her very useful in battle.
Sixth Ranger: The latest member of the Black Bulls when Yami formally recruits her complete with a squad robe at the trial, with the members revealed after the squad's early introduction (Zora, Henry, and Nacht) having been members since before the start of the story.
Zora: Lemme show my stuff as a senior member, Devil King!!
Nero: And don't forget the new member!!
Spanner in the Works: Although she doesn't reveal her true identity until the end of the first saga, Secre is responsible for some of the most important events in the entire story:
- Despite being introduced as a bird, she turns out to have been the first Wizard King's servant, and becomes vital to defeating the true mastermind of the elf massacre Zagred, who mocks her for her seemingly useless magic, when she unseals Lumiere and Licht's soul and later Asta's damage during the battle, letting him re-enter his Black form to finally kill the devil.
- If she hadn't been on hand to unseal Lumiere from Zagred's trap, then Lumiere wouldn't have arrived at the wedding's location in time to save Licht from falling completely into despair. Seeing his old friend in such a horrified panic was just what Licht needed to pull himself together and recognize that Lumiere was not responsible for the slaughter of the elves.
- Her invention with Lumiere using her Sealing Magic, named "Swallowtail" after her, was used by Julius to resurrect himself as a thirteen-year old after being fatally stabbed by Patry, with Nero surprised and happy that their invention saved the life of someone who carries Lumiere's legacy.
- She had sealed a dying Tetia's wounds after the massacre at her wedding, with Nero not knowing she had survived and went on to have a child whose descendants would establish the village Elysia near the Heart Kingdom. This plays an important part when Patry and the Third Eye, who settled there after the battle with Zagred, bring the Magic Knights who were in the Heart Kingdom there after Vanica and her Dark Disciples' attack to teach them the elves' esoteric art Ultimate Magic.
Species Surname: Her last name "Swallowtail" comes from the swallow bird family.
Stalker without a Crush: As an anti-bird, she has been following Asta all this time to keep tabs on Licht's former grimoire, which had been taken over by a devil. However, although she first did so for the sake of her mission, over time she began to care for Asta and believe in his dream to become the Wizard King after witnessing him overcome many challenges.
The Stoic: Nero is generally very calm and composed, as both a bird and human.
Subordinate Excuse: Because of her seemingly useless magic, Secre became the servant of Lumiere and very loyal to him because of his acknowledgement of her worth and dream of equality, with it strongly hinted that she developed romantic feelings for him. Sadly, he dies shortly after he's unsealed as a statue.
Sugar-and-Ice Personality: Usually Secre is pretty reserved and highly practical as a mage, especially given her crappy childhood for being treated like garbage over her seemingly-useless magic. Her experiences with Lumiere greatly brightened her up into a more normal person, and after gradually recovering from being an anti-bird for several hundred years and the trauma of Zagred's actions as well as Lumiere's sealing and death, she does finally start to sweeten again in the present. Albeit, with a bit of difficulty or hesitation, as it's clear she's not used to it.
Supernatural Sealing: Secre uses Sealing Magic. Originally, she thought that her magic could only open and close objects like locks, making it useless. However, she learned to seal magic into objects and even close wounds and seal damage. Using the power of Forbidden Magic permanently affected her Sealing Magic, letting her imprison a devil for centuries.
Supernormal Bindings: After using the magic stones, she can use her Sealing Magic to trap enemies in a cube. She does this to Zagred, and later adds Mana Method to it to bind Vanica, which would have worked if not for Megicula's Curse-Warding Magic.
Support Party Member: Nero's Sealing Magic is not offensive in nature, making her a Stage Six in combat ability. However, it provides many different supportive spells for allies like sealing enemies as well as wounds and pain.
Taken for Granite: Using the power of the magic stones, she sealed a dying Lumiere as a statue. She unseals him five centuries later after the Shadow Palace appears.
Team Pet: She acts as this for the Black Bulls before she reveals her true identity, with Asta and Noelle even debating what they should name her before she chooses Luck's suggestion, "Nero".
Tears of Joy: She cries these when she learns that Tetia, whose injury she sealed and didn't know her fate as she awakened as a bird long after, survived and gave birth to her surviving twin child, whose descendants established Elysia.
Theme Naming: Nero, the name of the infamous Roman emperor, follows the Roman statesmen naming theme with Julius the Wizard King, king Augustus, and much later on Lucius, which hints that there's more to Nero than she looks.
Token Non-Human: Of the Black Bulls as Nero, who can transform into an anti-bird, is no longer human after using Forbidden Magic with the wegs on her head as a permanent aftereffect.
Took a Level in Idealism: Having been looked down on all her life and getting relegated from a noblewoman to a royal servant for having a seemingly worthless magic, Secre had a cynical outlook on the kingdom and its royalty until she met Lumiere, whose dream of equality inspired her and gave her more confidence in herself as she honed her magic alongside him. This faith in Lumiere's dream continues with Asta, who she has confidence in to achieve his goal of becoming the Wizard King to better society.
True Blue Femininity: Calm, graceful, and has a dark blue grimoire and her black hair and dress is given a blue tint in the anime.
Tsurime Eyes: She has eyes that slant upward as a bird and human, and is usually quite indifferent to others. Yami calls her and Zora "team angry eyes".
Undying Loyalty:
- She serves as Asta's loyal companion ever since their first meeting. After watching him throughout his journey, she truly believes that he can achieve his dream of becoming the Wizard King.
- For 500 years, she's this to Prince Lumiere a.k.a. the First Wizard King, using Forbidden Magic to keep him alive and watching over the Clover Kingdom for centuries to help him stop Zagred's plan.
Utility Magic: Secre's magic was considered useless because it was thought to do nothing but open and shut things like locks and doors, with her seeing her own magic as vulgar. Spending time with Lumiere, who recognized her potential, allowed Secre to hone her magic to create magic items, close wounds, and even confine enemies from the use of Forbidden Magic.
Vitriolic Best Buds: Although she constantly pecks Asta on the head due to the latter's low magic, it becomes clear that Nero's concerned about Asta's welfare. She fully believes that he can become the Wizard King, but he'll never compare with the original.
Walking Spoiler: It's hard to talk about Nero in detail without revealing her true identity as a servant of the First Wizard King.
Was Once a Man: Nero states that she's no longer human after her use of Forbidden Magic to try to get the Black Bulls to not save her at the Magic Parliament trial. They tell her that they don't care and are going to save her anyway, moving Nero.
Weak, but Skilled: Her Sealing Magic isn't overtly powerful, ranking her a Stage Six in combat ability, but it has a variety of effects like sealing damage and imprisoning enemies that make it very useful.
Nero (to Undine): Unfortunately for you, ability alone isn't a measure of our power.
When She Smiles: Lumiere was one of the only people that could get her to smile, but after Zagred's finally defeated and she can start adapting to modern human life again, she does offer a genuinely sweet smile.
Who Wants to Live Forever?: Lived for 500 years as an anti-bird after forbidden magic made her inhuman, living only for her mission. She notes that the ridiculous amount of time would have broken her mind had she been in her human form.
Worth Living For: She considered joining Lumiere in the afterlife as his body crumbled away until he told Secre that he wanted her to reach her full potential and remain with the Magic Knights. His words come true when the Black Bulls save her and Asta from the Magic Parliament and wholeheartedly accept her into the squad, with Secre moved by their kindness and officially becoming a Black Bull. She thinks of how they're the friends who saved her and reason she stayed alive all thanks to Asta, begging for him to come back as a Paladin Damnatio defeats them.
Wrong Context Magic: Thanks to her Sealing Magic being an Ancient Magic affected by her past use of Forbidden Magic, Nero is classified as an Arcane Stage, a mage with inexplicable powers, on the Magic Stages scale. This is despite her being only Stage Six in terms of combat ability. Nero being Arcane is her, Noelle, and Lolopechka's trump card to seal Vanica's devil power, which almost works if not for Megicula's Curse-Warding Magic.
You Are Not Alone: Told to her by the Black Bulls when they welcome her into the squad, after she tells them she had used them for her mission to save them from the Magic Parliament. Nero is touched and accepts their gesture, joining the squad.
You Are Worth Hell: Nero was willing to use Forbidden Magic with her Sealing Magic to save Lumiere's life by turning him into a statue, at the cost of turning her into an anti-bird for five centuries. As his body finally crumbles away after the battle with Zagred, she tells Lumiere that she's willing to go with him to the afterlife, with him refusing as he wants her to achieve her true potential. As he finally dies, Nero holds his hand and tells Lumiere it was an honor serving him with tears in her eyes.

Characters / Black Clover: Secre Swallowtail

All spoilers on this page are left unmarked. You Have Been Warned!

Secre Swallowtail/Nero

Voiced by: Hitomi Sasaki (Japanese, bird form), Ayane Sakura (Japanese, human form), Monica Rial (English)

Debut: Chapter 2 (Manga), Episode 3 (Anime)

Magic Attribute: Sealing

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Characters / Black Clover: Secre Swallowtail

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All spoilers on this page are left unmarked. You Have Been Warned!

Secre Swallowtail/Nero

Voiced by: Hitomi Sasaki (Japanese, bird form), Ayane Sakura (Japanese, human form), Monica Rial (English)

Debut: Chapter 2 (Manga), Episode 3 (Anime)

Magic Attribute: Sealing

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