Board Thread:Improvements and Issues/@comment-33728110-20200802224044

Retsu is never shown to be using kido with her bankai, only before she activates it. Kenpachi is also never shown to make contact with the liquid. The liquid only is seen when she first activates bankai. Kenpachi is back to normal after explaining that he was "asleep" before. Kenpachi is also seen as a skeleton in the pages between chapters of the Nnoitra fight. It's a metaphor.

In Bleach Brave Souls Kubo very often supervises or advises on character designs, but the skeletal Retsu makes no appearance in her bankai and neither does burn or poison (to imply acid). 