Celica A. Mercury
"It's not good to go all out, Minerva."
Celica A. Mercury
Standing still (XBlaze)
Celica Ayatsuki Mercury (セリカ＝A＝マーキュリー), sometimes known as the Sister, was the younger sister of Nine the Phantom. She was an excellent user of sorcery, being one of the few people in existence capable of exceptional healing sorcery. After surviving the Dark War, Celica became a nun and looked after Ragna the Bloodedge, Jin Kisaragi, and Saya before she was brutally murdered by Yuuki Terumi. Kokonoe materialized a copy of her soul from when she was a young woman.
Celica wielded at different times the Nox Nyctores - Deus Machina: Nirvana and the Ex Machina: Minerva. She made her debut in BlazBlue: Phase 0 before appearing in BlazBlue: Chrono Phantasma. Celica was made playable in BlazBlue: Chrono Phantasma Extend and, as Little Sister, is one of the main protagonists of XBlaze Lost: Memories.
Celica is a young woman with medium-length brown hair she wears in a ponytail and red eyes. She wears a standard Mage’s Guild uniform of a white shirt and black cape with gold trim, a red ribbon around her neck, a black and gold skirt, and brown steel-toed shoes.
Celica has an unusually long lifespan due to aging very slowly, and only looks slightly older almost a century later as the Sister. During the time she watched over the remains of the Black Beast, she dressed like a typical nun of the Roman Catholic Church.
As a child, Celica had shorter hair and wore a short pink and white dress with long sleeves and an orange bow around her neck.
A young lady with a positive personality, who is kind to everyone. Her directional sense is beyond abysmal, and often it takes her several hours to reach a destination a few hundred meters away. She supresses seithr by nature, and holds the "Power of Order" within herself.
Powers & Techniques
The person who raised Ragna, Jin and Saya. A gentle yet strict woman.
She's one of the few pure sorcerers who is able to use magic without relying on seithr. She was tasked with protecting the area in which the Black Beast's fragments lay. However, Terumi murders her in cold blood, deciding she would interfere with his plans. 
Celica A. Mercury
Someone who doesn't belong in this timeline, a Chrono Phantasma.
With Kushinada's Lynchpin as the key to activation, Kokonoe replicates her soul from the past, and binds it to a vessel in the present. As such, Celica does not show up on the Master Unit's or Takamagahara's records, which makes her 'un-Observable.'
In her normal timeline, she would be attending the Mage's Guild's school. She's Nine's younger sister, one of the Six Heroes. She is unbelievably cheerful, and is optimistic in virtually every situation -- she also never backs down on a point, once she's made up her mind.
She heads to Japan in search of her missing father, and meets Bloodedge along the way, which will end up changing her fate forever.
Since birth, she was adept in the usage of healing magics, which is one of the reasons she is able to suppress the forces of the Boundary. Her ability to nullify seithr is perhaps nature's way of resisting its influence.
Her sense of direction is hopelessly awful, but for some reason she is not aware of this fact. 
Appearances in other Media
- BlazBlue 10th Anniversary Site (JP), Celica A. Mercury
- BlazBlue: Central Fiction Consumer Edition Official Site (JP), Celica A. Mercury
- BlazBlue: Chrono Phantasma Official Site (US), Celica A. Mercury
- BlazBlue: Central Fiction, Library Mode, Character #054
- BlazBlue: Central Fiction, Library Mode, Character #057