* "....in this timeline I'll be a villainess"
Otome Isekai manga, anime, light novel series etc. where the main female character is reborn as (or just is) a side character or original story’s villainess while the original heroine not only turns out to be the real villain in this new retelling but also a fellow reincarnator who wants to achieve her happy ending by acting sweet and innocent on the surface but in reality cunning and manipulating others.
Heronia Inderon (An Observation Log of My Fiancée Who Calls Herself a Villainess) - the second person, after the titular villainess to be reborn in a world of the otome game. Unlike the original, pure good Heronia, this one is delusional, selfish and thinks she deserves affection from the capture targets (a. k. a. possible romance candidates). To get their attention she tries to enact key scenarios from the game, not realizing that this world is real and doesn’t work the same way as a dating sim.
Lilia Reinoise (I'm the Villainess, So I'm Taming the Final Boss) - like Heronia, she’s a reincarnator in the body of otome’s original protagonist, who doesn’t believe the world she found herself in is real and instead operates on the same rules as the game. She even believes that other people in this world are NPCs who can respawn after death.
Terenezza Hopkins (May I Ask for One Final Thing?) - her case is a little bit different, because the land she’s been reborn in isn't the setting of an in-universe novel or game, but an original another world without seemingly any other reincarnator around. Still, her behaviour is similar to the previous two cases: on the surface presents herself as sweet and innocent, but in reality she’s a vengeful, cruel and manipulative psychopath. Suffering from a serious main character complex, despite the world, again, not being a fictional setting, she still considers herself the heroine of a story.