1.
Shao Yao transmigrated.
She ended up in a dilapidated temple, forced to disguise herself as a boy and play a little monk. To stay alive, she spent a full ten years looking after an injured, bad-tempered Buddhist cultivator.
After all that pleading and bargaining, she still couldn't escape having the Great Compassion Mantra recited over her and being reduced to ashes in one fell swoop.
Shao Yao: (╯°Д°)╯︵┻━┻!
Before she could recover, she transmigrated again.
This time, she became an intellectually challenged princess who spent every day playing "My Tyrannical Little Brother Is in Love with Me" with a perverted young emperor. She finally endured long enough to receive permission to pack her things and get out, but the moment the city gates opened, eighty thousand enemy troops had their arrows drawn.
Shao Yao: ...(^_^), fine.
On a battlefield where defeat was certain, the instant an arrow pierced her throat and her blood splashed across the city wall, the sky and earth suddenly changed.
First came the lords of the four directions, returning from ten thousand miles away. They chanted Buddhist verses, with lotus flowers blooming beneath every step.
Then came countless wailing vengeful ghosts. Black flames blazed a path, and thousands of mandala flowers bloomed.
That day, not a single one of the eighty thousand enemy troops survived. They were buried in a blood formation.
With her throat pierced and unable to speak, Shao Yao pointed at the impeccably dressed, white-haired heartthrob before her. Old grudges and fresh hatred surged in her heart, and she silently spat blood (and swears): You demonic fiend, pretending to be a monk! I curse you to die a miserable death!
2.
When Shao Yao opened her eyes once more, the transmigration-into-a-book System, which had arrived late, finally loaded into her sea of consciousness. It told her that all her previous misfortunes were because she'd transmigrated into an ancient novel that had been left unfinished for eight hundred years, becoming a cannon-fodder character mentioned only in passing on the villainous Boss's path to power.
The only way home was to help the power-fantasy protagonist become the top disciple of the immortal sect, point his sword at the leader of all demons, and hurry toward a happy, harmonious ending ahead of schedule
Unfortunately, after she actually entered the demon realm, the epic battle she'd imagined somehow turned into nothing but... the latest gossip sweeping the entire demon world.
The Demon Lord's beloved white moonlight is back!
The Demon Lord went to the northern frontier to pick flowers for his wife again today.
The Demon Lord is cooking for his wife again today.
The Demon Lord is... again today...
Wait!
Shao Yao and the original protagonist stared at each other.
Th-this plot development... why doesn't it seem right?
3.
Later, she found out.
She wasn't the only one who realized this was merely a book, nothing more than an illusion.
This story could also be called: Does That Demon Lord You Mentioned Have Hair?; I'm Done Being the Ruler of the Demon Realm!; The White Moonlights the Demon Lord Tragically Lost Over the Years Were All Her.
Theme: Human will can overcome fate.