Since ancient times, there have been books responsible for all of Earth's civilisation. These books were written with all sorts of myths, stories, living things, sources of science and technology.The book was protected by the "Holy Sword" and the "Selected Swordsman", keeping the world in balance. However, thousands of years ago, an attempt was made to steal the books. The books were scattered around the world and disappeared. This battle raged on in secret.In the present day, novelist Kamiyama Touma has a recurring dream: In another world, a swordsman fights a fierce battle with a monster in a book, and a mysterious girl seeks help. Every time he dreams about it, Touma is caught in the feeling that he is forgetting something important, but he doesn't know what that is or who the girl is. It seems that everyday life can collapse so easily. The dream always happens without warning.Suddenly, a strange phenomenon occurs where part of the city disappears. Important family members, friends, lovers disappear in front of each other's eyes.On the other hand, part of the disappeared city appears in a mysterious world."Where are you?" "What happened?" "How can I get back?" The desperate people wonder.Touma and Mei Sudo, the editor-in-chief, are suddenly involved in this phenomenon. Surprisingly, the other world is very similar to the dream that Touma often has, and like the dream, mysterious monsters invade and begin to destroy the city."I will definitely bring the city back to its original world!" Suddenly, a flaming sword appears as if responding to Touma's thoughts. As soon as he picks up the sword, he wields the power of the dragon, becoming "The Swordsman of Fire".