After the war known as the "Thousand-Year Blood War" had passed, the Quincy and Zero Division had almost completely perished, bringing about far-reaching changes to the world.
After the former First Division Lieutenant, Chiba Makoto, sat upon the throne and became the Soul King, he personally went to Hueco Mundo to subdue Aizen Sōsuke. Granting him the title of "King's Half-Body," he brought Hueco Mundo fully beneath the King's majesty as well.
Afterward, with his great power, Soul King Chiba Makoto separated the Seireitei from the Soul Society and completely fused it with the ruins of the Soul King Palace, creating New World City—a place where outstanding humans, Soul Reapers, Hollows, Quincy, and other races could coexist peacefully.
The former Thirteen Divisions were accordingly reformed into the Thirteen World Protectors Divisions, with Unohana Retsu continuing as Captain-Commander. However, the positions of division captains were no longer restricted to Soul Reapers, and openings were extended to all races.
Moreover, the new laws issued by Soul King Chiba Makoto put forth the concept of "Three Realms, Three Rulers," stipulating that Soul Reapers governed the Soul Society, Great Hollows governed Hueco Mundo, and humans governed the World of the Living.
From that point onward, privileged classes such as the nobility were eliminated from the Soul Society. All Soul Society resources belonged to all residents of Rukongai; combined with the liberation of resources, labor, and thought, as well as Soul King Chiba Makoto's deliberate guidance—
The Soul Society soon achieved true equality for all, transforming it into a paradise-like destination for souls. Every soul needed only to contribute a little labor to live a prosperous life.
Even those who wished to become Soul Reapers were equally welcomed by Shin'ō Academy, whose headmaster was Yamamoto Genryusai Shigekuni.
The souls of the deceased in the World