Yuhi Amamiya's everyday college life is interrupted when Sir Noi Crezant, a talking lizard who claims to be a Knight of Justice, informs him that the mage Animus intends to use the Biscuit Hammer—a colossal orbiting structure—to smash Earth to pieces. As a Beast Knight, Yuhi is meant to unite with others to protect the princess and save the planet, but he initially refuses, preferring to avoid danger. His quiet existence is shattered when a golem sent by Animus attacks him, nearly overwhelming him until his neighbor, Princess Samidare Asahina, comes to his rescue. Her surprising desire to destroy the world fascinates Yuhi, driving him to train and become stronger in order to help her. In the battles against Animus's forces, Yuhi gradually learns to cherish life more deeply, even as his past traumas continue to trouble him.