Busa Neko ni Kaerareta Kiyowa Reijou desu ga, Saikyou no Gunjin Koushaku ni Hirowarete Kizetsu Sunzen desu

Cursed to be an ugly cat--but maybe you're happy! "I'll have you turn into a cat, sister." Marie, the viscount's young daughter, lost her fiancé to her younger sister Emilia and has been cursed even more. Her reflection in the mirror - an ugly cat! Running away from her sister for her life, Ma...

Source: MyAnimeList