A herbivorous dinosaur stumbles upon a lost egg and raises the hatchling, only to discover it's a carnivorous dinosaur. Naming him "Heart," she raises him alongside her own offspring. When Heart realizes he must eat meat to survive, he leaves in shame. Years later, he encounters a similar situation with an herbivore hatchling, Umasou, whom he can't bring himself to harm. Reluctantly taking care of Umasou, Heart grapples with the complexities of predator and prey in a harsh world.