Just Breed is a strategy RPG released only in Japan for the Nintendo Famicom.

Long ago, in a time of legend. The country of Rumbleville is said to have prospered. Protected by the power of the seven sacred stones and guided by seven guides, the country was said to have been promised eternal peace and prosperity. However, when an evil shadow fell on one of the stones, Rumbleville was destroyed in an instant. The seven imams with the sacred stone led their people on a journey in search of a new land. One night, many years later, in Astholm, a town blessed with a sapphire stone, Phyllis, a girl from a family that has inherited the stone, is performing the annual Sapphire Festival, the first ceremony after becoming a new priest. The festival is in full swing, the ceremony goes off without a hitch, and Phyllis meets up with the town's garrison leader, a boy, at the edge of the village. Suddenly, however, a monster appears and snatches Phyllis away. All that remains is the sapphire Phyllis was wearing. The next day, with the sapphire in hand, the boy and his fellow garrison members set out on a journey to save Phyllis.