My Sister Who Regressed Wants My Fiance

Nereis is ordered by her father to become engaged in place of her older sister, who is favored by him. After running away for a week, Nereis enters the public domain, where her sister arrives and tells her to give up the position she once refused. Her older sister now wants to be the Ghost Duke’s wife, while a peacock who only approaches Nereis says he likes her. The strange turn of events deepens when Nereis finds her sister’s diary and learns that her older sister appears to have regressed—and has returned to claim Nereis’s fiancé.