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.

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.

Ryoka is awakened by flurry of text messages from her mother! Panicked and rushed, Mom is clearly concerned for Ryoka's safety, but she is not too keen on letting her daughter know why. Her reasoning being that nothing could really properly describe what is happening! The world might be ending! And there might be a massive new life-form on the roof of their apartment building! (Source: Denpa)

Third season of .