Nagi (凪)

A hundred years ago, a single magician suddenly appeared and bestowed magic upon the people. In a world where life has been dramatically enriched, there is a girl named Haru who despises the magic that brought misfortune to her own family. The person she encounters is Kanna, a Dispeller who can undo the magic that is the symbol of human progress and is feared as a heretic by the world. Their meeting sets in motion the judgment of the sins arbored by the greedy magicians... An epic fantasy saga that exposes the truth of magical society!!

I was reincarnated as Diana, a villainess destined to be the final boss, and I was living with the Ice Duke, with whom I was already in a political marriage, and his daughter, who feared me. My fate was to one day be defeated by my daughter's heroic lover—but I refused! I'll shower my daughter with love, improve my relationship with my husband, and aim to avoid becoming the final boss!! The story of a quirky duchess escaping her villainous status begins in grand style★ (Source: Kadokawa, translated)