BB , known as Mysterious Black Magus is the original promotional materials, is a character resembling Sakura Matou in Fate/Extra CCC. She is the creator and master of Alter Ego in Sakura Labyrinth.

BB is a backup AI created by Sakura containing her feelings for Hakuno Kishinami. During the preliminaries, she, who had her freedom unleashed by the hands of Kiara Sessyoin, could not control that abnormal status and caused an overload. Because the NPCs cannot do anything but routine work, they ignored Sakura who began to disintegrate as something "nonexistent" and since the Moon Cell's check was performed only at the end of the day during the preliminaries, Sakura was in a crisis of being extinguished. Upon laying his/her eyes on such abnormality, Hakuno called out for her saying "Are you all right?" By receiving the observation from another that "I'm right here", Sakura recovered her unconsciousness that was on the verge of being extinguished and acquired a clear ego of "I want to be here" due to the subsequent nursing. She escaped from the extinguishing of her ego.

Once the next day came, everything would be deleted by the hand of the Moon Cell. Sakura wished to continue this miracle of a mere day and employed the privilege of a high grade AI and repeated the "single day when I got to know Hakuno" for 69 days. However, as the day advanced Sakura began to suffer with her self-contradictions as an AI and the reality surrounding Hakuno.

Sakura kept suffering from the selfishness of eternally looping those happy times and her feelings towards Hakuno. In conclusion, she chose the path of sealing away the 69 days worth of memory. She sealed the memory of "love" that she acquired in order to turn back into a normal AI. AIs cannot delete records, so she reset herself by moving the memory to a backup unit, believing that this would be the most correct choice for Hakuno. However, even after losing the memories of the mind, the reminiscences recorded in the body survived. She was supposed to have forgotten everything and turned back into a normal AI but she started to be shaken up by an unidentified emotion-value whenever speaking with Hakuno. On the other hand, the backup where the memories were moved to one day decided her own plans as BB. BB became the rebel that disrupts the system of the Moon Cell for the sake of a certain objective and began to take action.

In real time, the timing when she seized the Far Side of the Moon was "the end of the fifth round prior to the start of the sixth round of the Holy Grail War". The four who had not been defeated yet were Hakuno, Leonardo B. Harwey, Rin Tohsaka, Rani VIII and the irregular Jinako Carigiri. They were midway through the Holy Grail War until they were kidnapped to the Far Side of the Moon while still alive. Masters that were defeated in the Holy Grail War such as Shinji Matou, Monji Gatou and Julius B. Harwey were moved to the imaginary space "0.00001 seconds before" being annihilated by the Firewall, extending their momentary lives.

At any rate, C.C.C. is a dream seen by BB. If the one seeing the dream disappears, the world should return to the prior reality where nothing happened. Also, this is a digression, but the ordinary scenery that Hakuno saw as a nightmare in the beginning was an artificial paradise built with those abandoned 69 days as a model. After BB dragged Hakuno to the Far Side of the Moon, she enshrined Hakuno in the electronic brain of the old school building, imprisoned into a deep sleep and a dream that Hakuno could not wake up from. Normally Hakuno would spend time peacefully in that looping everyday, but due to the strong link with Hakuno's Servants or maybe Hakuno's will to reject the peaceful repetitive days, tears arose on the artificial paradise and Hakuno became aware of the abnormality.

BB attempted to reset the school building and start over the dream in order to once again throw Hakuno into a deep sleep, but Hakuno also ended up escaping from that reset and jumping into the further depths of the imaginary space. That was the bottom beyond even the bottom of the id. The "collective unconsciousness" beneath the unconscious. What saved Hakuno, who ended up jumping into a territory that even BB could not reach out, was the voice of the Servant who shared fate with them. Thus the contract was exchanged and Hakuno woke up in the old school building that was left in the Far Side of the Moon.

BB had created the Sakura Labyrinth and later the Alter Ego known as the Sakura Five . All five Alter Ego resemble her and Sakura. She had killed off Run Ru and took Lancer as her servant.

Appearance

BB bears a resemblance to Sakura Matou with her long purple hair and eyes. BB wears long black coat with a matching skirt and wears a white shirt with a red bowtie. She also wears white gloves and black stockings.

Personality

While she gives off an evil inclination, she is described as "not as bad a person as she seems." She was developed to be different than Dark Sakura, more like an "impish underclassman." She notes that she doesn't mind being called "BehBeh" or "BayBay" because girls like her who talk with their hearts are like that. While BB and her Alter Egos normally only pay attention to Hakuno, Meltlilith instead goes after Archer if he is paired with the female Hakuno. If there were a girl BB and Sakura were based on, she likely would have longed after someone like him/her.

Fate Extra CCC OP

(Source: Type Moon Wiki)