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.

Fifteen years have passed since the war between humans and demons began. Dissatisfied with their slow advance into the Demon Realm, the Hero abandons his companions to quickly forge ahead towards the Demon Queen's castle. Upon his arrival at the royal abode, the Hero makes a startling discovery: not only is the Demon Queen a woman of unparalleled beauty, but she also seeks the Hero's help. Confused by this unexpected turn of events, the Hero refuses to ally himself with his enemy, claiming that the war the demons have waged is tearing the Southern Nations apart. However, the Demon Queen rebuts, arguing that the war has not only united humanity but has also brought them wealth and prosperity, providing evidence to support her claims. Furthermore, she explains that if the war were to end, the supplies sent by the Central Nations in aid to the Southern Nations would cease, leaving hundreds of thousands to starve. Fortunately, she offers the Hero a way to end the war while bringing hope not only to the Southern Nations, but also to the rest of the world, though she will need his assistance to make this a reality. Finally convinced, the Hero agrees to join his now former enemy in her quest. Vowing to stay together through sickness and health, they set off for the human world.

Mary Smith is a clumsy girl with wild red hair who can't seem to do anything right. After moving in with her Great Aunt Charlotte, Mary finds herself lonely and bored, until one day she spies a cat which seems to keep changing color every time she sees it. Curiosity gets the better of her and she follows it into nearby woods. Deep in the forest, the cat takes her to a clearing with dead trees and brown grass, where the only sign of life is a cluster of mysterious blue flowers that Mary has never seen before. The gardener of the estate later tells her that the rare species is called Fly-by-Night, and is said to be sought by witches for its incredible magical power. When the strange cat returns to her one night, Mary is led once again into the woods, but this time to an old broomstick hidden by a gnarled tree. After she clumsily squashes some Fly-by-Night against the broomstick, it begins to glow, whisking her off into the sky. Her wayward journey ends at the Endor College for Witches, where she is mistaken for a new student. And so, Mary must learn to look after herself in this marvelous new world of magic, where things are not always as they seem.

Shorts played before Made in Abyss Movie 3: Fukaki Tamashii no Reimei in Japan's theatrical screenings.