Sukuna's Little Sister Is Struggling to Survive Again

[Main story in the third person] [Countdown to the end of the main story] You live in an ordinary family during the Heian era. Life is uneventful, though somewhat poor. The only problem is that the villagers treat your family strangely, as if they fear and loathe something, yet still maintain peace on the surface. Until one day, you accidentally overhear your parents' private conversation and learn that you have an older brother after all. A... monster of a brother with four arms and two faces, supposedly the son of disaster. You suck in a horrified breath and frequently check your own body. After that, you pretend nothing happened and live a superficially peaceful life. Until one night, you are awakened from your sleep and discover the village engulfed in flames, while your parents kneel before an unfamiliar man and beg for mercy. Four arms, two faces. It is your monster of a brother! You see your monster brother sneer, wave his hand, and cut your parents into eight pieces. He looks up and sees you, then waves his hand again... You drop to your knees with a thump where you stand. Your legs gave out, that is all, you are not a coward! You urgently awaken your cursed technique and successfully intercept the slash that almost turns you into eight pieces as well. Your monster brother raises an eyebrow and carries you away. You silently shed tears as he carries you through the wind, hoping that one day you will be able to avenge your parents. You spend a long time following your monster brother through a miserable life in which everyone wants you dead. Finally, one day, a huge group of people joins forces to attack your monster brother. You are delighted, mingle among them, slack off whenever possible, and work as a traitor on the side. Your monster brother dies. You shed a few crocodile tears first, and apart from a faint sense of loss in your heart, you celebrate wildly. You are killed in the same way, surrounded and attacked by them. Because they believe Ryomen Sukuna is no good, and therefore you, who stayed by his side, must be no good either! When you open your eyes again, a thousand years have passed. There is no annoying brother, and no jujutsu sorcerers to get in your way. It is practically a perfect retirement life! Until one day, while casually passing a café, you hear a curse wearing human skin and two other curses discussing their grand plan to resurrect Sukuna as if no one else were around. ??? Who? Who are they going to resurrect? They say love is the most twisted curse. Sukuna is certain that his little sister must be cursing him viciously, every minute of every hour for a thousand years. So what if their flesh has perished? Their souls will surely remain entangled for all eternity, cursing each other. tip: You can start directly from the end of Chapter One and continue with Chapter Two~ Notes: 1. This story is not about loving each other dearly. It is about sabotaging each other, loving and fighting each other. 2. It contains quite a lot of elements: pseudo-incest, coercive love, a tiny bit of narcissism (?), and nonhumans. So, does the original-form grandpa count as a nonhuman? 3. The heroine and Sukuna are not related by blood. Sukuna knows this from beginning to end, while the heroine only learns it later. 4. The pairing is Sukuna. 4. A crossover with Noragami, Demon Slayer, and Jujutsu Kaisen. Much of it is heavily altered, and many timelines differ drastically from the original works. Please forgive the out-of-character portrayals. Theme: Strive! Stay positive! Keep moving upward!