Yasutora "Chad" Sado is revealed as the true mastermind behind all of Bleach and the final villain of the Howl From The Jaws of Hell Arc. The Hell Butterflies were used as conduits for the "Jailers of Hell's" clairvoyance abilities back in the day to know how events unfolded. After Yhwach's reiatsu was sent to Hell (while his corpse remains as the Soul King), everyone there absorbed portions of it, gaining clairvoyance similar to Jugram's - though not as perfect as Yhwach's Almighty. This dark energy manifests in the new bodies similar to the new forms of the Ghouls and Szayelaporro from Hell.
Chad fabricated the abuelo story to get close to Ichigo, who possesses abilities similar to Jugram that enhance those around him. Chad deliberately played weak to avoid suspicion. His Hollow-like powers, which Urahara and others found unusual, actually connect to Hell itself. In the greatest betrayal since Aizen, Chad kidnaps Kazui, planning to use him to merge Hell with the living world and destroy other realms. Chad is confirmed as the strongest character in Bleach, with the ability to manifest others' perceptions of him - as evidenced by Ichigo's quote: "I can never see Chad losing."
full cycle I know!
His brooding, distant demeanor masked the inner turmoil of maintaining these deceptive relationships. His Fullbringer powers weren't derived from Ichigo's "Hogyoku" like abilities - they
were something far more sinister all along.
