Nekomimi Majutsushi no Joshu Honjitsu mo Noroi Biyori.

Charlotte graduated from magic academy at the top of her class and was set to become an assistant to the highly paid royal magician. A rosy life was promised to her... But then, a letter suddenly arrived canceling her job offer, and it all crumbled away. She couldn't forgive such unreasonable treatment! To find out why, Charlotte headed to the sender, the royal magician, Clive, but... She found a man with cat ears and a tail! A love comedy about a magician who is currently reclusive due to a curse, and his cat-loving assistant, as they try to break the curse!

(Source: Ichijinsha, translated)