Over a million years ago, the progenitors of the Five Noble Clans betrayed the Spirit King, using the Soul King's power to divide life and death and create the Three Realms.
However, the progenitors of the Five Noble Clans were not the Spirit King after all. Though they had divided the Three Realms, those realms were fundamentally unstable and could collapse at any moment.
At the critical moment, under the influence of the Soul King's Will, Ichibei Hyosube turned the Spirit King into a "wedge" that stabilized the Three Realms.
To protect the Spirit King, Ichibei Hyosube formed the "Soul King Palace."
There were two ways to join the Soul King Palace and become a member of the Royal Guard. The first was to create something that had never existed in Soul Society. Those acknowledged by the Soul King's Will as people who had "created Soul Society's history" would receive an invitation. They could endure the Soul King's power and replace their own bones with an Oken condensed from the Soul King's power, thereby ascending to the Royal Guard and gaining strength far greater than before.
It could be said that every member of the Royal Guard possessed the "Soul King's Bones."
At present, the Royal Guard had four official members and one candidate.
Ichibei Hyosube had named everything in Soul Society.
Shunshunmaru Shutara had created the Shinigami uniform.
Nimaiya Ōetsu had created the Zanpakuto. Every Zanpakuto's prototype had been forged by him.
Tenshiro Kirinji had created the "Healing Art," allowing his own spiritual pressure to become hot springs that healed injuries. His blood-red spiritual pressure could even instantly restore those on the verge of death.
The final candidate was Kiryuo Hikifune, the current captain of the Twelfth Division. He had created "Temporary Soul," as well as cuisine that completely