Why nobody remembers my world?

Kai's duty as a member of the Human Protection Agency is to ensure that the four races from The Great War are kept sealed in their graveyards. Humanity has been at peace for 100 years, until one day a portal opens and the world he's known ceases to exist.

In the graveyard where the demons were entombed in his world, Kai finds a girl whom he cannot identify as any of the known races. When she asks him for help, he doesn't hesitate for long. After freeing her from her chains, mysterious things happen again.

After the demon attack on Neo Vishal, the resistance launches a major offensive against the demons and their heroine with the help of Kai and Rinne. But will Kai's knowledge from his world and Rinne's powers be enough to defeat the demons?

While Kai and Rinne confront the heroine of the demons, one of those mysterious beings reappears and tries to remove Vanessa from the world. However, Vanessa manages to fight it off. She then turns her attention back to Kai and Rinne.

After finally driving the demons out of the capital, Urza's resistance sets out for the Federation of Io, whose resistance has requested support against the divine beings. However, it quickly becomes clear that not everyone welcomes this support.

Jeanne and Urza's resistance encounter remnants of the Io resistance in the Elfan Forest. Following the trail, they arrive at the Elf Village, where the leader of the elves is already waiting to present them with a proposal.