Hizuki, who had been working herself to the bone in politics, was suddenly bound to a System one day and dropped into a world where humans and demons lived together.
The System announced: [Host, please expand your influence, change the protagonist's fate, and compete for the world's energy! Otherwise, after the mission ends, the System is entitled to take you before its core consciousness to face judgment.]
So you're threatening to put me on trial? I have to expand my influence and change the protagonist's fate?
Hizuki, who had somehow been dragged in to work for free, gave a cold laugh and rolled up her sleeves. "You may not know what my family did before I became a spiritron master!"
And so the System bore witness as his Pan-Star Cult and Paradise Church squared off, vying to recruit the "demons" from the original story as their subordinates. Like a raging mudslide, they transformed the world so thoroughly that even its own mother wouldn't recognize it.
Watching Hizuki corner the Demon King and casually claim Infinity Castle for himself, the System's creator slapped a hand to their forehead. Why did you have to provoke him?!
Content warnings: Sword spirits will appear. Jujutsu Kaisen serves as background and flashbacks, with little presence in the story. You can read this without having read the author's other book.
By the end, the protagonist and the System will learn to work together and get together. Canon couples won't be broken up. Canon pairings the author doesn't get won't be given an ending. Given the effects on the timeline, the younger kids probably won't get together either (definitely).
There will be a few hints of Douma having special feelings for Kotoha. Feel free to imagine it as friendship, romance, or something else. Open ending.
The focus will be heavily on family affection. Siblings won't develop feelings beyond familial love for each other.
Not friendly to fans of certain villains. The author intends to send everything flying.
The timeline will bend to accommodate the plot, and the author will make things up where details are uncertain.
Theme: Do what you can, and help others.