Gōkei

is a bankai technique used by Byakuya Kuchiki's Zanpakutō, Senbonzakura Kageyoshi.

Description
This form increases the number of tiny blades immensely. It creates a spherical formation of innumerable blade fragments, which swirl around the opponent like a cloud. It then flies into them from every possible angle, leaving no blind spots and no possibility to escape. It then collapses on itself, obliterating the opponent. It was strong enough to completely obliterate a very large building from the inside out, and the resulting shockwave generated by the attack is so powerful that Byakuya himself has to Flash Step away.