A low-ranking mage working at the royal castle, Maris, finds a badly injured black dog one night and decides to take it home. She names the dog Kuro and begins caring for it. After a certain incident, however, it is revealed that the dog is actually the missing hero who saved the nation, Zerek Windsorcoat. Everyone around them is shocked by Zerek's return, but Maris is shocked for a different reason: no matter how she looks at him, Zerek still appears to be a dog. Zerek, for his part, is openly possessive and devoted to Maris, behaving more like an affectionate pet than a celebrated hero. The story follows the strange domestic and romantic relationship that develops between the two as Maris struggles with her perception and Zerek's unwavering attachment. As their bond deepens, it draws them into a larger incident involving Zerek's past, the origins of the curse that gave him a dog form, and a connection to the royal family's ancient legend.