Senkei

When Byakuya's blood glows and turns to spiritual energy, it merges with his Bankai's minute blades and pulls them together into whole, luminous swords, thousands of them in all. They stack into four rows that hover just above one another and circle steadily around Byakuya and his opponent, walling the pair into a shared arena.

Senkei is a form of grim resolve, one Byakuya reaches for only after he has sworn to cut an enemy down with his own hands; Ichigo Kurosaki was merely the second being ever to witness it. It trades away defense for a single-minded devotion to offense.

By condensing the Bankai's scattered blades into far fewer swords, Senkei loads each one with much greater cutting power, so a handful of strikes can gravely wound where the unfocused Bankai would need many. Byakuya usually calls the swords to his hands for melee, at which point their glow fades and each takes on the look of his sealed blade, though they can dissolve back into a swarm of tiny blades at will. The cage keeps both fighters close while leaving room to maneuver. After his training in the Royal Palace, Senkei grew to at least six rotating rows and could loose every sword at once; its ultimate strike, Ikka Senjinka, impales a target beneath thousands of blades launched in one volley.