Oblivion's Throne - Chapter 119: Sweet Sorrow

A side story series featuring the girls of Kyoukai Senjou no Horizon.

He is a young man without a spirit root. It is believed that this denies him the chance at cultivation. However, a mysterious lady imparts a Supreme Demon Classic to him and from then on, he starts his path of cultivation.
He undergoes a total transformation to emerge as the most fearsome and powerful fiendish demon in his era, that even immortals and fiends are fearful of him, and saints are at his beck and call.
Mastering the Supreme Demon Classic is the turning point in his life. He is able to unleash his immense and divine power from within, illuminating the entire universe!

- Description from Novelupdates

The world changed the day that cracks appeared in the sky– suddenly monsters named『Demonic Beasts』appeared and began to rampage, attacking people.

Meanwhile, girls called『Magical Girls』began to appear to counter the demonic beasts. As they defeated the demonic beasts, gradually people’s lives gained a semblance of composure.

–but when there is light, there is also darkness.

In the corner of an alleyway, a boy who had been attacked by a demonic beast was dying. His voice begging for help did not reach anyone and his body refused to move.

「Boy. Do you want to be saved?」

Looking into the boy’s face, a black cat began to speak to him.

The boy nodded firmly to the devilishly sweet invitation, in response the black cat mocked him.

「Is that so—then I’ll【Haunt (Save)】you」

—on that day, a『Magical Girl』was born in a place that no-one knew.

『She』never laments, no matter what the future may bring.