The story of Happy Breeding revolves around Takashi, who has just started living on his own. One day, he finds a strange girl in his house, and they decide to live together. As the days go by, more girls move in, each with their own unique animal traits. Takashi's life becomes more lively than expected, but also brings unexpected challenges.
The gameplay of Happy Breeding is typical of a visual novel, with players interacting with the characters through dialogue choices. The game features static character models and animations, as well as full voice-acting for the main heroines. Players can use fast-forward options during dialogues to speed up certain sections of the story. With its unique blend of adventure and simulation elements, Happy Breeding offers a fresh take on the visual novel genre.