The Book of the Black Bulls is the first Black Clover light novel written by series creator Yuki Tabata and illustrated by Johnny Onda. It was released in Japan on August 4, 2016. Set from the perspective of the Black Bulls, the novel tells the story of how they first met the runaway Diamond Kingdom commander Fanzell Kruger.
The first half takes place shortly after the main storyline begins, in which Asta befriends Fanzell and becomes his student. They briefly encounter Mariella, a former student who's now working for the kingdom as an assassin and is plotting to take back Fanzell to help them finish experimenting on Mars. Eventually, Asta tells Fanzell he must find a new reason to live before going their separate ways.
Five months later, after Asta is injured during his battle with Mars, Fanzell asks the Black Bulls to help search for Dominante while dealing with the Diamond Kingdom's assassination squad.
The novel was included in the anime adaptation as a two-part episode, which takes place during the Forest of Witches arc.
The Book of the Black Bulls provides examples of:
- Batman Gambit: Knowing how her work as an assassin for the Diamond Kingdom is really like, Mariella plots to exact revenge on the organization and turning herself in to the Clover Kingdom's Magic Knights by luring the Black Bulls into having her squad captured while she goes to the black market to inform Domina that the group would be arriving there afterwards.
- Call-Forward: You might remember Fanzell, Dominante and Mariella in Black Clover as the people who aid the Black Bulls in entering the Forest of Witches to cure Asta's arms.
- Comes Great Responsibility: Fanzell agrees to train Asta on one condition: that he may not use his powers to harm the weak and only reach his goal to become the Wizard King.
- Continuity Nod:
- The Magic Knight Entrance Exams are briefly mentioned.
- Dominante Code is originally from the Forest of Witches who left for Fanzell, a man. By the time of Black Clover, the forest is infamous for having an Evil Matriarch who doesn't like men.
- Defector from Decadence:
- Fanzell and Dominante defected from the Diamond Kingdom because they grew dissatisfied with its corruption.
- Mariella quickly becomes a renegade within the Diamond Kingdom's assassination squad as she tells the Black Bulls her plans to destroy the organization. Unfortunately, Galleo decides she has become a liability and plots to execute her.
- Et Tu, Brute?: Fanzell's reaction to Mariella stabbing him in the back with her ice dagger and revealing herself as an assassin is utter shock.
- Flashback: The anime adapts this story as a series of flashbacks, which occur shortly after the beginning of the Forest of Witches arc and gives greater context on who Fanzell, Dominante and Mariella are.
- Foregone Conclusion:
- Since the first half takes place a few months after Asta receives his grimoire, the latter will explore the dungeons shortly after he and Fanzell go their separate ways.
- By the end of The Book of the Black Bulls, it was established that Mariella has already joined Fanzell and Dominante in exile, Asta and the Black Bulls will enter the Underwater Temple, and Domina and Fanzell will be husband-and-wife. Mariella trying to take down the Diamond Kingdom will also be doomed to fail.
- Greater-Scope Villain: The Witch Queen casts a shadow on Dominante while the Diamond Kingdom's assassination squad serves as the advance force for Mariella.
- Heroic BSoD: Fanzell goes through a brief one bordering on Despair Event Horizon when Mariella tells him that Dominante might have been killed.
- In the Back: When Mariella tells Fanzell about how his students were killed by the Diamond Kingdom's assassins, she uses her ice dagger to stab him in the back.
- I Want Them Alive: The Diamond Kingdom explicitly instructed Mariella to bring back Fanzell alive so they can have him help finish experimenting on Mars.
- Karma Houdini: By the end of it all, Mariella joins Fanzell and Dominante after Galleo is defeated. But her job as a Professional Killer involved a lot of criminal activities such as providing intel and murdering defectors, and she knew that she would face severe punishment had she turned herself in to the Clover Kingdom's Magic Knights. Even so, it will take a serious effort for her to atone for her crimes.
- Let Us Never Speak of This Again: At the end of the story, Yami makes this demand to Gauche after they assist Fanzell in helping the Magic Knights capture the Diamond Kingdom's assassins.
- Multi-Part Episode: The anime adaptation splits the novel into two parts, called "The Man Named Fanzell".
- Naked People Are Funny: Asta first sees a naked Fanzell being chased by a boar.
- Origins Episode: The light novel explains how Asta and the Black Bulls befriended Fanzell, Dominante and Mariella.
- Reports of My Death Were Greatly Exaggerated: When Mariella captures Fanzell and Asta in their house, she tells them that Dominante may have already died because the latter's wand was stained with blood. However, it soon turns out that she's alive and well.
- Screw the Rules, I'm Doing What's Right!: When Fanzell is captured by Mariella and her squad, he tells Asta to get out of his house and reminds him to use his powers to achieve his dream. Asta ends up fighting Mariella and helping Fanzell anyway.
- Training from Hell: Asta undergoes intense training from Fanzell when they first meet. First, he picks up several logs for him and then, they commence their sword training.
- The Woman Behind the Man: Mariella is behind the plot to help the Black Bulls in atoning for her misdeeds as an assassin and avenging her fallen comrades.