One day, a massive dungeon suddenly appeared in the sky. In response, humanity developed the ability to generate “wings” to fly and challenge this mysterious airborne labyrinth. In this new era of skyward adventurers, Kojiro Kijiya, a high school student who is the only one unable to generate wings, is branded as a hopeless failure — a “dropout.” Yet, despite being unable to fly, Kojiro refuses to give up. Thus begins the tale of an underdog’s daring challenge to conquer the sky dungeon!