Arcueid Brunestud (アルクェイド・ブリュ ンスタッド, Arukueido Buryunsutaddo) is one of the five main heroines of Tsukihime, and often considered its "main" or "default" heroine - in any case, she is the most popular Tsukihime heroine. She is the eponymous Tsukihime (Moon Princess), as evident by the title of her "True Ending."
Arcueid is described as the main heroine of Tsukihime. Aside from her own route in the game, she is the character with the largest role in a route not her own, that of Ciel. However she makes nearly no appearance in Akiha, Hisui and Kohaku's routes, while Ciel does make some limited appearances.
Shiki Tohno will first meet Arcueid in one of the 2 "Near side of the moon" routes (Arcueid/Ciel's routes) after leaving school early one day because of an anemia attack, he spots Arcueid on the street and is consumed by an irresistible urge to kill her because of his Nanaya blood. The Nanaya were a family of killers that specialized in hunting down non-humans, and Arcueid as a vampire awoke his Nanaya blood. Skillfully trailing Arcueid back to her apartment, he rings the doorbell and in the instant the door opens, sneaks through the crack and slices her into 17 pieces in an instantaneous single strike with his knife and his Mystic Eyes Of Death Perception. Regaining his sanity and finding himself in front of her corpse, Shiki staggers to the park where he either collapses and is taken back to the mansion by Kohaku (Arcueid's route) or is found and taken care of by Ciel (Ciel's route).
The next day when heading to school, Shiki finds Arcueid waiting on a guard rail outside his school. Panicking, he runs, only to be chased into a dead alley and confronted by Arcueid. Their conversation is interrupted by one of Nrvnsqr's beasts, and Arcueid "convinces" Shiki to help her deal with the vampire in the town as she used up most of her power to re-form her body after Shiki killed her and will need time to regain the power she had lost.
The two of them are partners against Nrvnqsr Chaos, with Shiki killing Nrvnsqr by striking his "death point". They decide to again be partners to take out Roa who Arcueid has been targeting. Over the course of her route she and Shiki begin to understand one another. Shiki shows Arcueid the various things she's unaware of, such as movies, which are things Arcueid can't comprehend as important. At several points she attempts to bite Shiki, though she manages to hold herself back in time, though usually she runs until her impulses have stopped. Eventually she and Shiki have fallen in love with one another, despite her slightly unstable nature and vampire lineage. However, she attempts to take out Roa by herself and is apparently killed in the process. Enraged and in grief, Shiki proceeds to destroy the walkway he and Roa are on as a distraction and utterly destroys Roa's point, thus nullifying his very existence and preventing him from ever reincarnating.
In Arcueid's True Ending, Shiki waits in his classroom for her despite thinking she is dead. Arcueid surprisingly arrives, having regained the bit of power Roa stole from her. However she can no longer hold back her impulses and decides she should sleep from now on, dreaming of Shiki. Despite Shiki's pleas, even begging her to drink his blood, Arcueid says she can't do so because she loves him and says farewell with Shiki greatly saddened, looking at the moon as he leaves the school. This ending was the basis for the ending used in the anime, although a few details were changed. In Arcueid's Good Ending, she spends an entire week suppressing her urges and meets Shiki on his way to school. The two then go off to seemingly spend the day together.
Arcueid is also one of 2 possible successors to the original Crimson Moon. The other is her "sister" Altrouge Brunestud, but she is generally considered too "unstable". All that is known about their relationship is that they had a fight some time after Arcueid fell and Altrouge won. That was also the fight where Arcueid lost her long hair when Altrouge took a portion as her trophy.
Arcueid Brunestud is the white princess of the Shinso, the True Ancestors. The title of Brunestud was given to those shinso capable of manifesting the Millennium Castle Brunestud, and has been likened to be the vampire royal family, although this is not strictly true. The True Ancestors were a race of beings copied from TYPE-MOON, the ultimate being of the moon, also known as the Crimson Moon. Long ago the planet had no defense mechanism against humanity, nothing to keep them in check. Thus the Crimson Moon came down and offered to help the planet make a race of ultimate beings to rule over humanity. However the race was fundamentally flawed, they had a desire to drink blood that the original, the Crimson Moon had. The True Ancestors needed to use a large portion of their power to suppress this impulse, but as there was no cure, and with passage of time the impulse grew, more and more True Ancestors fell and began drinking blood indiscriminately, while others most likely went into eternal sleep.
Thus the True Ancestors created Arcueid as a weapon, the executioner of the fallen True Ancestors and Dead Apostles, the most powerful of them all. She was able to perform this duty splendidly, but she was nothing more than a tool. She knew nothing except whatever details were necessary to go after her target, and went to sleep after every kill, with her accumulated memories erased.
As the executioner, she did not have any vampiric impulses, and the rest of the True Ancestors also believed she had none. A priest from the church seeking perfect immortality, Michael Roa Valdamjong, needed to become a Dead Apostle to continue his research as he had already reached the potential of his human body. He hid blood in a rose and offered it to Arcueid, who not knowing she was not supposed to drink blood, drank it and in the process fell, becoming berserk and wiping out most of the True Ancestors and turning Roa into one of the strongest Dead Apostles before she managed to regain her sanity long enough to chain herself to the throne and go to sleep. From then on she had to suppress her urge to drink blood like any other True Ancestors. The rest of the True Ancestors were wiped out either by Roa or the rest of the Dead Apostles who made a game of trying to assassinate their creators.
Arcueid finally managed to destroy Roa's original body, although it took an alliance with the Burial Agency to do it. Roa was not killed however, as he had managed to master re-incarnation, and constantly re-incarnated into host bodies he chose before his deaths. These host bodies were chosen for a mix of social standing (rich families with influence) and the physical/magical potential of the body. After destroying Roa's original body, Arcueid went to sleep and awoke only to kill Roa's re-incarnations constantly, but was never able to destroy him and get her power back as he would simply re-incarnate each time. At the time of Tsukihime, Roa had re-incarnated 17 times, with his last re-incarnation being SHIKI.
Arcueid is shown to be a whimsical individual who, although knowing the basics of the modern era, does not seem to know about social norms. Once, she shows up at Shiki's school and waves to him from the school rear courtyard, luckily for Shiki only Ciel spots her. Even more luckily, she doesn't do what she planned, which was jump up to his window and knock. Her behaviour is almost child-like, due to the lonely nature of her up bringing, although she is over 800 years old, she spent most of it asleep and knows nearly nothing about the world or how to interact with others. As she works together with Shiki to stop Roa, she gradually begins to enjoy life and starts to like Shiki as more than just a friend.
Arcueid does everything in her power not to drink Shiki's blood, which nearly occurs several times in game as he is practically the only human at night with her, and she has problems controlling her vampiric impulses after being drastically weakened by Shiki's attack. She doesn't want to drink blood, as she doesn't want to become a monster that feeds on humans in order to survive.
As the most powerful True Ancestor created to specifically hunt down the fallen True Ancestors, there are few who can match Arcueid in terms of strength, speed and endurance. Before Shiki killed her, she was using 70% of her power to suppress her vampiric impulses, but even then she was more than strong enough to destroy almost any Dead Apostle that got in her way; especially with her Marble Phantasm, which can literally change reality to create any naturally occurring effect and summon the Millennium Castle Brunestud, the ancestral home of the True Ancestors. The power of Marble Phantasm is such that even in her extreme weakened state, she was able to reduce Roa's latest host body to just the ankles.
She also has the normal vampire claws, and as a True Ancestor very few conceptual weapons can harm her. All vampires can ignore damage from most sources as their body will revert to the pre-damaged state rapidly, a conceptual weapon such as the Black Keys used by members of the Church nullifies this ability. At night she is almost invulnerable, and her power is at its peak during the full moon. During the night, all of her lines and points of death disappear, rendering her indestructible; however, they show up again when Shiki "kills" the very nature from which she draws her strength in one of the endings. She can not only regenerate most wounds rapidly, but even re-form her body completely after having her 'lines' cut by Shiki, even though it took the majority of her power to do so. She also has Mystic Eyes that enable limited control over others, such as the ability to plant suggestions. The color of her eyes changes to gold when they are active.
- Arcueid shows up as Neko-Arc in Ciel-Sensei's lessons, as well as the Melty Blood fighting game.
- Arcueid apparently can't stand garlic, as seen in a Kagetsu Tohya scene where she ate instant noodles cooked by Shiki that had garlic in them, and became sick. This is the only known instance in the Tsukihime games where garlic has an adverse effect on vampires.
- Arcueid desperately wants Shiki to continue cooking breakfast for her in the Melty Blood manga. Shiki managed to get Arcueid to apologize to Akiha by threatening to stop cooking breakfast for her, and she rapidly complied.
- Arcueid appears as Phantasmoon which is a result of watching a Magical Girl movie with Shiki. This form does not appear in any canon TYPE-MOON work (until Fate/Tiger Coloseum Upper) and is more or less an in-joke among Tsukihime fans which can be seen in other doujin works; for one example, Arcueid appears with this form in Battle Moon Wars, a dojin soft game developed by Werk. Upon seeing Rin Tohsaka's magical girl form, Kaleidoruby, Arcueid "upgrades" to Phantasmoon Eclipse. Her first appearance was in Take-Moon by Eri Takenashi.