Sword Art Online Light Novel Volume 19

Cradle of the Moon is a side story set after the events of the Alicization Arc. It is now some time after the events of Volume 11 and the world has gained peace. The people of the Human World, the people of the Dark Territory, the Goblins, Orcs, Ogres, and Giants have all signed a unity peace treaty and the Dark Territory and the Human World have opened up for trade. After the War of the East Gate and Rebellion of the Four Empires the four Imperial Noble Families (assumed to be the Ancestor Families mentioned in the Alicization Arc), who had been oppressing the common people had finally been overthrown and Underworld seems to be at a state of peace. The Underworld Fundamental Law has been introduced and the Taboo Index revised. In a few years the Integrity Knights will become the largest fighting force in all of Underworld and among them will be Ronie, Teiza and their dragons: Tsukigake and Shimosaki who are currently Integrity Knight Apprentices.