Once upon a time, there was a world of enchantment and technology. Man's potential frightened God, prompting him to divide the world into two: Elde, the realm of science, and Fandavale, the world of magic. In Fandavale, a fearsome witch known as Cendrillon (Cinderella) is resurrected. She plans to dominate both worlds and hunts for the "key" that possesses immense power. Sōta, a young boy from Elde, meets Akazukin, a mysterious girl from Fandavale, and her talking wolf companion, Val. Sōta discovers that he is the key that Cendrillon seeks. Now, it falls on Akazukin, Val, and the other Fairy Musketeers to safeguard Sōta from Cendrillon and her Nightmarelians, who covet the enigmatic power he holds.