Sucks big time
Dropped after learning the truth.
Spoiler!
This is a classic, biased narrator trope story. The MC, was actually incompetent and less brilliant than her genius twin. So she resorted to self-harm.
So the twin (the "evil sister") pretended to be sick and useless so her twin could shine.
But that led the MC to mistreating her and pushing her into the shadows completely, taking credit for all the work the "villainess" did. Till she snapped.
Leading to the regression.
So ... you spend most of the Manhwa hating the sister. Only to learn that the Yandere, suicidal MC was the real villainess all along.
So the twin (the "evil sister") pretended to be sick and useless so her twin could shine.
But that led the MC to mistreating her and pushing her into the shadows completely, taking credit for all the work the "villainess" did. Till she snapped.
Leading to the regression.
So ... you spend most of the Manhwa hating the sister. Only to learn that the Yandere, suicidal MC was the real villainess all along.