Dare ni mo Aisarenai no de Yuka wo Migaite Itara Soko ga Seiiki-ka shita Reijou no Hanashi

Stella was never given the love of her family, nor the skills bestowed by God. After her fiance's heart was stolen by her younger sister, she rushed to a convent. She discovered the joys of cleaning and ended up becoming a maid for the troubled prince Cecil, who is holed up in a room filled with miasma. Before she knew it, she had acquired the skill of "purification"—and combined with his "destruction" skill, she transformed magical beasts into fluffy, holy beasts! Is there a secret behind Stella's origins?!

(Source: Gaugau Monster, translated)