On Raising a Seductive Demon Lord

While descending to the mortal realm to undergo a tribulation, Luo Shengge found a miserable little boy who was down on his luck and bullied by everyone. The boy turned out to be a descendant of the ancient ferocious beast Qiongqi, with its bloodline flowing through his veins. Luo Shengge couldn't bear to kill an innocent (not really). It was just one more mouth to feed. Was she really worried she couldn't raise a child? Luo Shengge: "Be good. From now on, call me Big Sister, got it? Don't call me Auntie or Old Aunt, or I'll beat you up!" The boy: "..." Wasn't she supposed to treat him gently? But later, when the boy witnessed Luo Shengge split her three souls and seven spirits and sink into a frigid pool to save all living beings, he chose to descend into the abyss and become a demon. Four hundred years later Luo Shengge, with only one soul and one spirit remaining, finally awoke from her long sleep. But the loss of her other souls and spirits had left her with gaps in her memory. When she saw the tall, handsome man before her, who followed her around calling her "Big Sister" at every turn, she was at a loss. Since when had she acquired such a grown-up little brother? Later, when a divine official saw them, he immediately shouted a warning to Luo Shengge: "Lord Luo, be careful! The person behind you is none other than the Demon Lord you once told me about, the one who kills without mercy, eats the living, and is best at beguiling people's hearts!" [Bonus Scene 1] When Xize was little Luo Shengge: "Wow, our Aze is so adorable! Big Sister just loves cute boys!" (Hugs him and smothers him with kisses.) So when the Demon Lord Xize grew up, he deliberately acted cute to get close to his Big Sister. But later, when Xize heard his Big Sister discussing her "type of man" with her girlfriends Xize pinned his Big Sister against the door of the divine palace and leaned close to her ear. "I hear you like them wild, Big Sister?" Xize: "You really are changeable, Big Sister~ No matter. Aze can be whatever you like." [Bonus Scene 2] Demon Lord Xize: "Big Sister, I'm the most obedient person in the world." Luo Shengge: "Liar! When you pinned me down and had your way with me over and over, why didn't you listen to me?" Demon Lord Xize: "Because you once said women never mean what they say, Big Sister. Aze remembers every single thing you've ever said!" Luo Shengge (holding her aching lower back): "...A Yuan was right. You really are a dog of a man." Demon Lord Xize: "Have you forgotten, Big Sister? I'm a big cat~" (Qiongqi's true form is a big kitty.) [Reader's Guide] 1. The story starts four hundred years later, with flashbacks to the past (four hundred years earlier) woven throughout. 2. A sweet, doting romance with mutual affection. There will be a little angst along the way, but no misunderstandings between the leads. 3. A big-cat male lead disguised as a loyal puppy × a seemingly gentle, carefree female lead (who is actually insanely powerful). 4. This story has plenty of original worldbuilding. The demons, monsters, gods, and spirits are largely inspired by texts such as the Classic of Mountains and Seas. 5. This is a lighthearted story about immortals and demons, so please don't nitpick the details. The setting features six realms: gods, immortals, demons, devils, humans, and ghosts. Theme: The desire to protect all living beings has never belonged only to gods or demons.