|“||The sealed King of the Quincy. Over 900 years, he shall recover his heartbeat. Over 90 years, he shall recover his intellect. Over nine years, he shall recover his power. And over nine days, he shall recover the world. Let us go forth. Uryū. Haschwalth. These nine days will be the end of this world.||„|
|~ Yhwach to Uryū Ishida and Jugram Haschwalth.|
|“||The path has now closed. Ichigo. The path to a world without fear. The Human World, Soul Society, Hueco Mundo. They belong together as one. They should have been brought together, that life and death may mingle as one. But now that path exists no longer. All thanks to you, Ichigo. How disappointing. Because of you, life and death will not lose their form. All living things will continue to live their lives in fear of death...for all eternity.||„|
|~ Yhwach to Ichigo Kurosaki.|
He is adamant in his dislike of conflict to the point where he will attempt to stop it at all costs, even if brutal methods are required. Yhwach's contempt for Arrancar is apparent, mercilessly wounding and slaying even those who have sworn allegiance to him when he deems them to have fulfilled their use. This same disregard extends to all his subordinates, regardless of species or rank, and is an attitude that he has allegedly always possessed.
Yhwach is the progenitor of the Quincy clan. Whether this means he is their ancestor or just bestowed his powers upon them is unknown at this point. About 1,000 years ago, Genryūsai Shigekuni Yamamoto fought him. Sometime around or during the course of this event, Yhwach witnessed the capabilities of Yamamoto's Bankai, Zanka no Tachi. After a bloody battle, Genryusai was able to seal Yhwach away by putting him into a seemingly eternal slumber.
Unknown to Genryusai, Yhwach was able to recover in the following millennium. After 900 years he regained consciousness. After 90 years he regained his intelligence. After 9 years he regained his former power by draining the spiritual energy of every living Quincy, leaving them either dead or vulnerable to Hollow attacks.
At some point during the seventeen months after the defeat of Sōsuke Aizen, the Vandenreich invaded Hueco Mundo, and Yhwach personally defeated its ruler, Tier Harribel. He imprisoned her, and claimed the territory of Hueco Mundo for the Vandenreich, regarding it as another foundation stone to invade Soul Society.
Later it's revealed that the old man Zangetsu is actually Ichigo's Quincy powers and it takes on the form of Yhwach in 1000 years ago.
- The prophecy of Yhwach recovering over a period of 999 years is reminiscent of the story of Revelations and the rise of Satan to dominate humanity. The number 999 is an obvious nod to the Number of the Beast (666).
- His name is similar to YHWH.