Miss Kobayashi's Dragon Maid(2013)

Kobayashi-san Chi no Maidragon

Miss Kobayashi is your average office worker who lives a boring life, alone in her small apartment–until she saves the life of a female dragon in distress. The dragon, named Tohru, has the ability to magically transform into an adorable human girl (albeit with horns and a long tail!), who will do anything to pay off her debt of gratitude, whether Miss Kobayashi likes it or not. With a very persistent and amorous dragon as a roommate, nothing comes easy, and Miss Kobayashi’s normal life is about to go off the deep end!

(Source: Seven Seas Entertainment)