Since the death of his parents, Shinpei Ajiro had lived with the Kofune family and their two daughters—Mio and Ushio. Although he then left his home island to continue his education in Tokyo, Shinpei returns after Ushio tragically drowns during the attempted rescue of a little girl. During the funeral, his best friend informs him about bruises found around Ushio's neck, casting doubt over the cause of her death. Suspecting a murder has taken place, Shinpei reevaluates recent events, but strange incidents only continue to transpire. Disappearing people and other unexplainable occurrences lead Mio to recall an old folktale referring to entities called "Shadows," which may not be entirely fantasy. Supposedly, an encounter with one's Shadow foretells the person's impending demise. Facing the dark side of Hitogashima Island, Shinpei stands against his grim fate to fulfill Ushio's final will—to protect Mio.

Kou Yamori is an average middle school student who struggles with grasping the complex concept of love. Because he sees little sense in surrendering to the norm, he soon stops going to school. Plagued with insomnia due to his idleness, Kou begins roaming the lonesome streets at night. One night, Kou encounters a bizarre girl named Nazuna Nanakusa who believes that people stay awake during the night because they are dissatisfied with how they spent their day and cannot rest until they release their inhibitions. Nazuna offers to help Kou with his sleep issues and invites him over to her place, where she convinces him to share a futon with her. Feeling uncomfortable, Kou only pretends to doze off—which is when Nazuna suddenly bites his neck and reveals herself to be a vampire! While Kou thinks the bite will turn him into a vampire, the specifics of transforming are not that simple. In order to change, he must be bitten by someone he truly loves. Ready to let go of his dreary mortal life, Kou decides on a new goal: he will fall in love with Nazuna and become a vampire.

Striking fear into the hearts of mortals, the Demon Lord Satan begins to conquer the land of Ente Isla with his vast demon armies. However, while embarking on this brutal quest to take over the continent, his efforts are foiled by the hero Emilia, forcing Satan to make his swift retreat through a dimensional portal only to land in the human world. Along with his loyal general Alsiel, the demon finds himself stranded in modern-day Tokyo and vows to return and complete his subjugation of Ente Isla—that is, if they can find a way back! Powerless in a world without magic, Satan assumes the guise of a human named Sadao Maou and begins working at MgRonald's—a local fast-food restaurant—to make ends meet. He soon realizes that his goal of conquering Ente Isla is just not enough as he grows determined to climb the corporate ladder and become the ruler of Earth, one satisfied customer at a time! Whether it's part-time work, household chores, or simply trying to pay the rent on time, Hataraku Maou-sama! presents a hilarious view of the most mundane aspects of everyday life, all through the eyes of a hapless demon lord.

Intrepid adventurer Bell Cranel has leveled up, but he can’t rest on his dungeoneering laurels just yet. The Hestia Familia still has a long way to go before it can stand toe-to-toe with the other Familias of Orario — but before Bell can set out on his next mission, reports of a brutal murder rock the adventuring community! One of Bell’s trusted allies stands accused of the horrible crime, and it’s up to Bell and his friends to clear their name and uncover a nefarious plot brewing in the dungeon’s dark depths.