Slime Seijo

The weakest demon (slime) who longed to be human is reincarnated as a saint, but with the worst character of all, a villainous noble girl. From the lowest status, hated and resented; an existence where she will be terminated immediately if her true identity as a slime is discovered, she will become a beloved saint in order to live a safe and secure life!

(Source: Shueisha, translated)