I Became A Gyaru In Yandere Sim

Rumiko died while being a former high school student, now she wakes up being known as the 1st miss also known as Mutsumi Rumiko does that name sound familiar? If yes, then you guess right that she became Mutsumi Rokuda's older sister.
Now in her high school years, she is known as the big sister of the bully group since they look up to her, and in the distance, she also has other people looking up to her but in a loving way.