|Spoiler Alert: This article/section contains details about future plotlines described in the light novels, not covered in the anime. Do not proceed unless you want to be spoiled. |
Some time after the War of the Underworld, Underworld entered a state of peace. The people of the Human Empire and the Dark Territory, the Goblins, Orcs, Ogres, and Giants all signed a peace treaty and the Dark Territory and the Human Empire opened up for trade and travel. After the Rebellion of the Four Empires, the four Imperial Noble Families, together with the entire noble system, had been overthrown. The Underworld Fundamental Law was introduced and the Taboo Index revised. The Integrity Knights were becoming the largest fighting force in all of Underworld. Ronye and Tiese became Integrity Knight Apprentices, along with their dragons Tsukigake and Shimosaki.
Kirito became the Representative Swordsman and de facto leader of the Human Empire Unity Council. He engrossed himself in the research and examination of his new creation, the «Mechanical Dragon». After a failed public experiment, Kirito revealed to Ronye that the «Mechanical Dragon» research was currently his highest priority as it was very likely for the imbalanced resource distribution between Human Empire and Dark Territory to cause another war. If the invention of the «Mechanical Dragon» would be successful, it might be able to cross the Mountain Range at the Edge, allowing the races of the Dark Territory real countries to live in, as their current territories were just stretch of barren land.
On the 18th day of the 2nd month of the Human Empire Calendar 382, a Centoria resident was killed, with a goblin visitor suspected to be the murderer. All visitors were required to agree on a set of rules before they were allowed to enter the Human Empire, which included a ban on murder. As the suspect's right eye still remained intact, indicating that the goblin did not violate the Seal on the Right Eye, Kirito and other members of the Council concluded that the goblin did not violate the rule and thus had not killed the Centoria resident. With no other suspects being identified and no apparent cause that could lead to killing of that Centoria resident was unveiled, Kirito and other members of the councils worried about the possibility that unidentified rebellion forces or Dark Sorceresses were behind the case to plot another great war. Kirito decided to head to Obsidia, the Dark Territory's Capital to meet with Iskahn, the leader of the Dark Territory Inter-racial Council, to reach an agreement as soon as possible.
- Reki states on his site that Cradle of the Moon is designed to be a standalone fantasy story, which happens to have characters with the same names as those from Sword Art Online.