[System + Possession + Secret identities + Cards + Cute pet interactions]
[Lots of unrequited crushes; the original pairings remain intact]
[No confirmed pairing for now; Doma is undecided]
[Characters saved so far: Doma, Akaza, Hantengu, Gyokko, Gyutaro, Daki]
After finishing Demon Slayer's ending and being left devastated, He Yue transmigrated into the world of Demon Slayer, only to become Muzan's inner demon.
She also activated the [Muzan Opposition System]. Once she accumulates enough of Muzan's rage, she can exchange it for a [Plot-Changing Card], which lets her control Muzan's choices in the story.
So He Yue spends every day messing with Muzan, finding new ways to mock him, then uses the rage points she earns to save all the characters whose tragic fates left readers heartbroken.
Possession changes her gender and appearance, but not her body's aura, so perceptive characters on both the demon and protagonist sides can sense who she is.
Each time she completely changes a character's fate, she earns a one-time-use card granting that character's strongest combat power.
Before being used, the cards can take the form of animated chibi characters, making them super fun to interact with!
[Not everyone gets a happy ending in the first round. A second round will begin.]
[In the end, even Muzan will find a different kind of redemption, with an unconventional happy ending.]
P.S. The heroine's surname comes from Xihe, the Chinese sun goddess.
This article is saved according to the timeline. The early stage is full of ghost plots, and the heroine is firmly in the decent camp. The protagonist group will be rescued only in the later stages, and the cps that are obvious in the original work will not be dismantled. Also, the author, please stop reading books, it's easy to die from reading books🥺