The King of Beasts
One day, deep in the heart of Chaldea, Ritsuka Fujimaru frowned and turned away from her comrades after yet another failed summoning. She smiled, as she always did, but she knew that they knew that her smile could not possibly be real.
She took their consolations and platitudes with that same empty smile as she left, returning to her quarters.
That night, she come to a decision. No longer able to tolerate the horrible Gacha rates, she turned to an old tome she found buried deep within the storage room.
Within were the details surrounding the summoning system they utilized to call upon Heroic Spirits. But more than that, within lay the secrets to manipulating that same system. It was her final recourse. A modified summoning ritual that was said to be able to increase the success of summoning a thousand fold.
Her many recent failures weighing heavily on her, she began to prepare the materials needed in the secrecy of her room. She was the last Master of Chaldea. She was the last line of defense standing between humanity and anything that threatened them. If this is what it took to succeed, then so be it.
And yet… her mediocre magical potential failed her once more. Rather than summoning a Heroic Spirit from the Throne of Heroes, the ritual instead tore open a hole in reality. Unable to resist the potent energies pulling her in, she found herself thrown into the void, beyond the flow of time.
Unable to return nor capable of anything else, all she can do is wait and hope that someone, Da Vinci perhaps, would find what she had done and come up with a way to rescue her.
But as time passed and no rescue came, all she could do was wait. Wait as her end approaches. And as she waited, she could not help but rage at the Gacha, the very thing that had forced her to perform the ritual in the first place.
Unknown to her, the failed ritual had a mysterious effect on both herself and her surroundings. The more time passed, the more she was changed, the changes directed by her subconscious thoughts. And those same thoughts further fueled her rage, causing the changes to proceed faster. And the more she changed, the more her rage grew. The more she raged, the more she changed.
Time passed, and soon there was little left of the Master of Chaldea’s former appearance. Her features would now be unrecognizable to anyone who saw her.
Soon, her rage grew to the point that it, along with her determination, was enough to tear a hole in space, allowing her to re-enter the world.
But gone was the Master of Chaldea. All that was left of the young woman she once was, was the desire to overcome that which drove her to despair. The Gacha.
However, it was not meant to be. It did not take her very long to realize that she had not returned to the proper time period. Here and now, an indefinite number of years before the Gacha even came to be, there was nowhere to direct her anger.
And so she wandered, now bereft of a purpose. And yet her anger continued to simmer, seeking an outlet even as it threatened to consumer her from within.
As she continued to roam the lands that would later become the world she knew, her eyes caught sight of something very familiar. A familiar sight that reignited the embers burning deep inside her.
Was it not humans who created the Gacha? Was it not humans who created the very thing that turned her into the monstrosity that she had become?
Her mind, twisted by her rage and eons of solitude, could come to no other conclusion.
Humanity created the Gacha. Humanity was at fault. And if she destroyed humanity, did that not mean that she would succeed in destroying the Gacha?
And thus, with her purpose renewed, the being once known as Ritsuka Fujimaru was reborn as Gudako, the very first Beast of Calamity.