I won't get around to this JJK story so I'll post my idea here. Totally a rip-off of some ideas from Twilight Poem but we're here for a good time, not making high art.
Twins, one born with celestial energy, and the other twin born without anything. The celestial twin is favored in the clan until in a terrible accident a cursed spirit manages to infiltrate their clan and steals her eyes, said to hold power beyond compare.
The celestial twin is turned on, and when she and her twin discover that they can utilize cursed spirit energy together, they send the other off to become a sorcerer and find the missing eyes.
The celestial twin is mistreated by the clan and secreted into a temple where no curse can harm a human but can gain strength.
The celestial twin meets a sorcerer named Sukuna, who becomes entranced by the divine power left in her body. He returns often and eventually manages to woo the girl, especially after she heard that her entire clan has tragically died in a terrible fire caused by a rogue curse.
He takes the celestial being in as his bride but makes her promise to never touch him, and to never trust anyone but him. His assistant, Urame, often advises the lady on how to attend to her Lord husband and tells her that the Lord Sukuna cannot touch her until he has 'prepared himself' for her.
Meanwhile, the sister returns to the Clan, having become a powerful sorcerer but discovers the terrible King of Curses, Ryomen Sukuna has destroyed her clan and stolen her sister in an attempt to gain immortality.
In a tomb, she discovers the secret manuscripts of Celestial Spirits, and how curses can use them to gain power. They may be killed to gain immense, godlike power, or if they fall in love, procreate and reach ascendance, they may ascend to the celestial realm and become gods.
The sister is able to reduce her spiritual power and sneak into Sukuna's temple, where she returns the eyes to her Celestial sister and tries to tell her the truth and get her to run away with her. But the sister is in love with her husband already, and so the sister forces her to take her eyes, telling her that her husband is a cursed spirit, killed their family, and is planning on killing her. This use of curse power gets the attention of Urame.
Urame has witnessed the interaction, but believing it better for Sukuna to kill the celestial being and take her power, decides to let her see Sukuna from afar. She witnesses him as he holds court with the other feudal lord, and realizes that he is indeed a monstrous cursed spirit and not just a sorcerer who could use them.
In despair, Urame leads her to Sukuna's throne room, where the bodies of countless are stacked to create Sukuna's throne. The Celestial Twin has a breakdown.
Knowing that she'll never escape, unable to live with herself causing the deaths of her family, and being unaware of Sukuna's true nature, she ends her life.
Her sister manages to take the body and burn it, so no other can use the power within. She also ends up unlocking immense power and helps contrive a plot to take down the King of Curses.
...
1,000 years later, two twins are born into a powerful clan. One is born with celestial energy, and the other twin is born without anything. They both work at their alma mater, Jujitsu High, only to stumble upon a young man who decided to eat a certain finger.
