Everyone knows not to mess with Kuro-sama, the old witch who lives in a gaudy old mansion on the outskirts of the village. The old bat even enjoys, no, takes pride in being called 'witch'. She views it not as an insult, but a fact of her superiority, and smiles fondly at her skull-and-snake tattoo whenever she hears the title. Though Kuro-sama is strongly disliked by all, awfully condescending and a down right menace to work for, she is none-the-less untouchable on Sandaime-sama's orders. Her miraculous healing potions saved countless lives during the second and third great shinobi wars, and have become a pivotal necessity in the hospital's procedures. Her safety and livelihood of luxury and extravagance guaranteed by the Hokage in exchange for mass production of various potions, there is only one thing Kuro-sama has continuously refused to do: take on a student.
"It is simply impossible!" She would assert. "Even if I taught you barbarians how to brew, none of you could possibly produce a viable potion. Your filthy inferior blood lacks magic." Her answer was consistent and it was not long until her words reached the ears of powers such as Danzo and Orochimaru. "If it is her blood that we need," Danzo thought, "Then it is her blood we will replicate." Determined not to let the entire medical system fall with the old witch's death, Danzo ordered Orochimaru to copy Kuro-sama's abilities. Unlike the shodai-hokage's wood release, the gene responsible for magic could not be isolated. Therefore instead of creating a genetically modified child like Tenzo, Orochimaru created an exact clone of Kuro-sama. Danzo then 'uncovered' Orochimaru's labs so that the child could be found and given to her original to be raised and taught the way of potion making. Of course, Danzo didn't let Orochimaru know it was he who had betrayed him as he still had uses for the snake. But not only did revealing and exiling Orochimaru achieve his goal in getting Kuro-sama a successor, it also turned suspicion away from himself as a co-conspirator of Orochimaru's.
Kuro-sama, the narcissistic hag that she is, was absolutely thrilled to find she had a clone. At least, that was how it appeared to the outside. In reality, Kuro-sama's insistence on her own magical superiority in a world without magic had left the bitter old woman isolated and lonely. It is not easy being the only one of your kind, after all, especially if you view those around you to be lesser and unworthy of your attention. It was the fact that the child had magic that excited Kuro-sama rather than that she was her exact copy.
In exchange for being given custody of her clone, Kuro-sama had to agree to the terms that she would take the child on as apprentice, forbid her from becoming a shinobi and enter her into an arranged marriage with Danzo's grandson. The marriage contract stipulated that all female descendants of the clone for three generations would be civilian potion mistresses and marry shinobi. Kuro-sama bargained that down to two generations and only those with magical ability, ("after all, marrying into your poor blood there's no guarantee magic will be produced") but otherwise her desperation for magical company won out and agreed to the rest of the terms. Kuro-sama raised her clone like a spoiled grandchild, taking on the role of doting grandmother in a way that absolutely terrified the shinobi who knew her.
Kuro-sama taught her clone all about her past and the world she came from, the war her people lost against the light. "Our side fought for tradition and purity." Kuro-sama explained. "Just as a beautiful and priceless work of art will fade in the sun, so too did we fear our ancient culture would be washed out into obscurity by the light side of the mudbloods. I remember it all," Kuro-sama would muse, "as part of this cursed punishment for my so called misdeeds, I can remember every aspect of my old life, every snippet of information I ever learned, but was forever lost to me when I was tossed into this retched world through the veil." Her wrinkled mouth would curl with the irony. "Everything I wanted to preserve was forcibly torn from me, leaving me with only my magic and my memory. It was meant as a taunt, I am sure, salt in the wound- for what is the use of magic without a wand? What can I do with memory of a world I have no hope of returning to?" Kuro-sama's face would always twist into a sneer at this point of the story. "Potion brewing does not require a wand, and though some ingredients are unavailable to me, I can use my wit to work around it. My knowledge of dragons and broomsticks and spells may be not be useful to me, but someday, with insight, they might be useful to you or your descendants." Then she would lead her clone to her library, where shelves upon shelves of tomes, hand transcribed from memory lay. "Here I give you the knowledge of a world, my sweet." Kuro-sama told her clone. "And when I die and my memories leak from my eyes, I shall bottle those too and give them as my last parting gift." Here she would reach into her frilly bodice for the empty vial she always wore on a silver chain around her neck. "So I am always ready." She would say. "To pass my memories to you." Then the old crone would smile, reassuring her clone and terrifying anyone else who happened to pass by, "But that may not happen for quite some time. Witches and wizards enjoy the blessing of longevity. Baring being killed we can look forward to living a long time yet."
Kuro-sama warned her clone often. "In order to enjoy our longevity, we mustn't trust them; the muggles. In my old world they hunted us down and killed us. It was only by hiding- taking shelter in the dark, did we survive, while those filthy muggles lived freely in the light. Their ignorance protected us, the Statute of Secrecy the only alternative to all-out war. But the naïve blood traitors thought they could allow mudbloods, magical children born to the other side, born in the light, into our safe haven of darkness. How foolish they were. Leave those atrocities to die, kill them rather than allow them to corrupt our society. That's what we believed. Alas, our darkened corner was burned by the light, our war was lost, our lord defeated, and magic of generations was ruined. Our loyal people were either killed in battle or thrown through the veil to be scattered across the multiverse. For a long time I despaired. I was the only one of our kind in this world of barbarians. And yet I persisted. I moved to a hidden village, thinking these ninja could relate, would understand what it means to thrive in the shadows. I was wrong. Shinobi are grey; the worst of both light and dark. They preach their will of fire, yet kill to make their living. They neither live blissfully unaware in Eden, nor hide from death in the dark. Instead shinobi stand with one foot in the light and one foot in the dark. They brought death into Eden and now nowhere is safe. Now more than ever, the odds are stacked against us: we number only two in this world, while they hold terrifying military power. You must promise me this, my child, my hope: give them potions; sell them what they want, but never show them your true power. Power seeds fear and fear seeds death. Do not trust them. Marry your intended, filthy though he may be. Use his seed to carry on our line. But do not forget our roots. We are the most Noble and Ancient House of Black."