I will Kill the Hero! With Fluff!

Three years after the hero had been summoned, demonkind is at the brink of extinction. Talia, one of the last generals serving under the rule of the great king Karion, is sent out to kill humanity’s only hope for winning the battle. She is helped by the magic of the great lich Sarato, who transforms her into the being the hero feels ‘most secure and happy to be with’. Little did they know this didn’t mean she would turn into a beautiful girl.