How is This Hot Duke Just a Background Character?!

Summary

After reincarnating as Leticia, a minor extra in an otome game, the "new" Leticia unexpectedly inherits her twin sister's engagement to Lionel, a rumored chubby and awkward duke-to-be. But Leticia sees the potential beneath his rough edges and takes it upon herself to help him grow. As Lionel transforms into a refined and handsome noble, his feelings for her deepen rapidly. Though she only wanted a peaceful life as an extra, Leticia suddenly finds herself at the center of an intense, ever-growing devotion from her now-irresistible fianc.