Odebu Akujo ni Tensei Shitara, Naze ka Last Boss Ouji-sama ni Shuuchaku Sareteimasu

After dying of illness, she has been reincarnated as Celine, the selfish, fat, villainous duchess, sister of the heroine of a popular novel. If she stays this way, she will be killed by the hero prince and die a miserable death, just as in the novel....