I'm the Older Sister of a Villainess, but I Don't Want to Die, Even If I'm Just a Mob Character

Giselle, the older sister of a villainess, faces downfall or death on every route. After remembering her memories from her past life, she begins re-educating her younger sister Odile, who is the source of all evil, to prevent her from becoming a villainess! What's more, Giselle's future fiancé is also a troublesome man who is certain to fall into the dark side...!?