The True Mistress Has A Thousand Hidden Identities - Chapter 22

One day, Luo Jian woke up from his sleep and found himself in a locked chamber where the door and window were all sealed. A note with a few lines written on it was tacked to the wall: “Escape from this room within an hour, otherwise, you will die.”

There is a sequel called Reincarnation Night (轮回之夜) that takes place in the same universe but has different main characters

- Description from Novelupdates

Bestselling author Elias Vayne has spent years writing stories to escape the horrors of his past. As a child, he was the sole survivor of a massacre that wiped out his entire orphanage. He doesn’t remember how he survived—only that when the slaughter ended, he was the only one left standing.His latest work, The Arcane Academy Chronicles, takes place in Veylin Academy, a prestigious school of magic and combat. But one night, after finishing the final chapter, Elias wakes up inside his own book—not as the hero, not as the villain, but as an extra. Worse, he’s been reborn as Kael, the very same orphan who survived a similar massacre in the story.But something is wrong. The academy isn’t as he wrote it. Characters are acting off-script, unknown forces are rewriting events, and the mystery surrounding Kael’s survival mirrors the one in Elias’s real life. The more he tries to regain control of the narrative, the more he realizes this world may not be his creation at all.

Once an imperial princess, now reborn among the lowest of s*aves of the nobility.