OOC: Of course you would pick Byakuya.
IC:
Kenji, having run out of options, sighed. "Brace yourself, Kaze."
He fired another black Getsuga Tensho, it's power filling the sphere in it's intirety. It's power also rebounded, reflecting it upon itself. It was, however, too much power for the sphere to contain; black Ki energy began leaking out of cracks forming on the sphere, before the sphere collasped in a massive, black explosion.
Kenji, exausted, let the power of Bankai slip away, his katana reverting back to a cleaver and his clothing changing back.
At least we're out of the sphere...