Manga details

Mitame Youjo na Akuyaku Reijou wa, Koori no Koutaishi (Tokidoki Kawaii) no Ude no Naka.

For the sake of her kingdom, the duke's daughter Juliana becomes the fiancée of Folkhart, the notoriously icy Crown Prince of the neighboring empire. Her guise? Using magic to de-age her appearance into the "4-year-old Princess Liane"—! According to Enzo, a valet who claims to have arrived from another world, this reality is actually an "otome game," and Juliana is the villainess doomed to absolute destruction. This is bad... at this rate, if the ruthless Folkhart uncovers the truth, both she and her nation will be wiped out! "But I will never, ever give up-deshu!!!"