User blog comment:Xilinoc/Ch. 591 - Marching Out the ZOMBIES 2/@comment-24282510-20140731035626/@comment-5398287-20140731050722

But it's just his Zanpakuto. The Bankai is the ice, just like the Shikai is mainly the ice and a slightly longer blade. It's not changing in shape from Shikai to Bankai, just allowing Hitsugaya to make more ice. But whatevs.