Long ago, in a land of myths and legends, a young girl named Rose prepares for her terrifying fate as the sacrifice for the sea beast Leviathan. However, a brave hero appears suddenly and defeats the creature, saving Rose's life. Filled with gratitude, Rose pledges her loyalty to Mikhail, her rescuer who is the demigod child of Diana, the moon goddess. She joins his group of adventurers but soon realizes that her savior may not be as honorable as she once believed.