In a city that only god remembers the name a dragon has fallen and created a crater, after a while a dark veil surrounds the city and monsters called nightmares pop up from the crater.
humans developed a way to fight the monsters, using a power coming from a wish made on a dream to the fallen dragon, Kurota Akiya is one of those fighters ( called Irrationals ) with powers ( called Dreams ).
After years of serving the city as an Irrational, and after a traumatic event with and old friend, he decided to quit and live the most quiet life possible but his quiet life is going to be interrupted soon by an encounter with a mysterious girl