While sleeping one night, Ryo Utsugi had a nightmare of monsters attacking him. One day he learns a mysterious power to let him hear voices and have visions of girls getting killed, but one night he hears the same voice. (Source: ANN)

The Demon Lord Tasogare's castle is a dark and frightening place, filled to the brim with various monsters. Any soul unfortunate enough to be imprisoned here is sure to be terrified by the horrors within. However, the human princess Aurora Suya Rhys Syalis Kaymin is a different case. Rather indifferent to her situation, Syalis worries about one thing and one thing only—sleep. Ever since the demon lord kidnapped her from her kingdom, she has not had a single good night's rest. To alleviate her dozen dozing issues, the princess makes do with what she can find in the castle. Whether it be the fur of fluffy demonic teddy bears or the silky, blanket-like bodies of ghost shrouds, everything is but a means to ensure a peaceful slumber. With so many potential materials to craft items that can help her sleep at her disposal, nothing will stop the sleepy princess—not even death.

Dreaming of a magical world every night, the young Toramizu Ginta yearns to be able to go there. With only his friend Koyuki believing in his dreams, Ginta remains positive despite the slander he receives from others over his dreams. But his wishes are answered, as one day a large door appears in front of Ginta, summoning him to the land of MAR Heaven. In this land, the weapons known as ARMS exist. While initially Ginta greatly enjoyed the discovery of this magical world, he soon learns of the terrible wars that have once plagued MAR Heaven and the upcoming war that may soon appear.

In this magical world, one is easily identified as having magical abilities by a distinctive mark on their face. Those unable to practice magic are swiftly exterminated to maintain the magical integrity of society. However, deep within a forest lies an anomaly in Mash Burnedead, who can be found pumping iron with one arm and lifting a cream puff with the other. This aloof boy with superhuman strength—but no magical abilities—leads a quiet life with his father, far removed from society. Mash's peace is soon disturbed when the authorities discover his lack of magical powers. They issue him an ultimatum: compete to become a Divine Visionary, which would force everyone to accept him, or be persecuted forever. To protect his family, he enrolls in the prestigious Easton Magic Academy, which only the most elite and gifted students are allowed to attend. Now, Mash must overcome his shortcomings as a magicless being and surpass the other students—relying solely on his muscles.