Prince Ike of the kingdom of Mano embarks on a quest to defeat the feared Demon King and free his people from terror. To get close to his enemy, Ike disguises himself as a woman, pretending to be a kidnapping victim. He nearly succeeds in landing a deadly strike, but the Demon King’s retainers knock him out before he can finish the job. When Ike regains consciousness, he finds himself not in chains but seated at a dinner table, being treated to a meal.

Determined to complete his mission, Ike declares he will not leave until he has defeated the Demon King. There is only one problem: the supposedly evil and all-powerful Demon King is a complete wimp. Every time Ike tries to attack, the Demon King runs away or hides instead of fighting back. These daily confrontations become routine, and Ike gradually learns unexpected things about his target. The Demon King treasures his houseplants, worries constantly about everyone around him, and even shows concern for Ike himself. As the two spend more time together in the castle, the lines between enemy and something else begin to blur, leading to an unexpected connection.