Inu wo Hirotta, Hazu Datta. Wakeari na Futari no Hatsukoi Jijou

"A hero who saved the nation?! But to me, he looks just like a dog!?" One night, Malice, a low-ranking royal castle magician, finds a badly injured black dog. She names him "Kuro" and decides to live with him in her home. However, an incident leads to the discovery that Malice's dog is the missing "hero who saved the nation," Zerek Windsorcoat! But to Malice, Zerek looks just like a dog. And it seems Zerek himself has an obsession with Malice...!? (Source: Kadokawa, translated)