In a time when the great war between five rival races for supremacy on Earth ended with humanity's victory led by the hero Sid, the world suddenly gets "overwritten" right before the eyes of a boy named Kai. In this rewritten world, Kai witnesses humanity's defeat in the war as a result of Sid's absence—where dragons and demons now rule the land, and Kai himself has become a forgotten existence to all humans. However, after encountering the mysterious girl Rinne, Kai resolves to break free from this rewritten fate. In a world without a hero, he inherits the sword and martial skills of the hero (Sid) and challenges the powerful enemy races that dominate the land.

Will Serfort dreams of keeping his promise to a childhood friend by becoming a Magia Vander, one of the mighty magicians who sit atop the Wizard's Tower. However, he is unable to cast even the simplest of spells, leaving him to fight dungeon monsters to earn credits at Regarden Magical Academy. As if that weren't enough, he finds himself putting his sword skills to the test against a bullying professor!

Kazuhiko Nukumizu, a self-proclaimed "background character," accidentally witnessed his popular classmate Anna Yanami being rejected by her childhood friend. Since then, Kazuhiko has become involved with several loser heroines, including Anna.

Eight-year-old Tokiyuki Houjou, the next successor of the Kamakura shogunate, is a young boy lacking talent in everything besides hide-and-seek. One day, his carefree life is abruptly turned upside down when Takauji Ashikaga brutally seizes power from the Kamakuras, ending their reign. Rescued by a self-proclaimed prophetic priest, Tokiyuki manages to escape with his life. Now he must evade those trying to kill him while recruiting comrades who can help him restore the Kamakura Shogunate to its former glory. Set during the Nanboku-chou period of Japanese history, is a tale of redemption, documenting the life of the forgotten hero that altered Japan's destiny by running away.