I Made Up Forbidden Spells, and They Actually Worked? - Chapter 24 - : The Surprise Brought by Nicholas

After getting betrayed and killed by the only person she’d loved, Miss Shang wakes up in the body of the cowardly crown prince Shang Wuxin, who, due to her own circumstances, was actually a girl cross-dressing as a boy. After inheriting the crown prince’s memories, Shang Wuxin has three things on her agenda:

1. Clean up the house

2. Gather loyal followers and soldiers

3. Get the throne

- Description from Novelupdates

One drunken night, my friend blurted out something absurd.“Su-Hyeok, I’ve regressed.”“Regressed?”“Yeah, I’ve returned to the past.”“Are you out of your mind?”“You’re humanity’s only hope.”Then, I was dragged into the tower for real… but who cares?Regressor? Tower? Trials? What are those supposed to be?An overwhelming talent is about to crush everything in its path!

Every novel has a slag character, the one who decides to abandon the protagonist at his lowest, most helpless point, either because he can’t stand the poor guy’s circumstances or for other reasons. But after the protagonist wins his way in life again, they’re the ones who beg with broken sobs to be taken back.

Still, water once spilled can’t be recovered again.

Yet the unlucky Shen Jiayan has been bound to a Water Recovery* System to do just that.

*water recovery – comes from an idiom that means “spilled water can’t be recovered” (English equivalent: there’s no use crying over spilt milk).

- Description from Novelupdates

Protagonist travels between different anime worlds to right wrongs and uncover his reason for being along the way.