The dragon slayer Leon was defeated and captured by the Silver Dragon Queen. With his life on the line, he tried to use forbidden magic to curse the dragon queen, but the curse had unexpected side effects, and the queen lost control as they had a one-night stand. He thought that the shame she would carry for the rest of her life would be enough to fulfill his life's purpose as a dragon slayer. But two years later, when Leon opened his eyes, he found a young dragon girl with a tail sleeping next to him…

The Abyss represents annihilation, instinctively swallowing up all life. But one day, a traitor appeared amongst the Abyss, as the girl Helga woke up confused, only to find out that she was actually the feared being known as the "Midnight Abyss." As she experienced life with humans, she became convinced to use her Abyss powers to defend humanity and to save what was good in the world. But the chaotic forces of the Abyss would not let her go so easily... (Source: Tencent, translated)