Through a twist of fate, a herbivorous dinosaur discovers a lost egg and carries it back to her nest. When the egg hatches, however, a carnivorous dinosaur emerges. Unable to abandon the offspring, she names him "Heart" and raises him in exile alongside her own child. As Heart matures, he struggles to consume the same food as his family and flees in disgrace upon realizing he cannot survive properly without meat. Years later, the now-feared predator Heart encounters a situation mirroring his past—he spots a dinosaur egg belonging to a different species. As it hatches, Heart remarks that the newborn looks delicious. The newborn herbivore assumes Heart is his father and adopts the name "Umasou," meaning delicious-looking. Unable to eat a newborn who loves him, Heart reluctantly decides to raise Umasou as his own. As he nurtures a forbidden child, just as his mother did before him, Heart struggles to cope with an unforgiving world and the true natures of predator and prey.