User blog comment:Xilinoc/Ch. 616 - Mimihagi-sama/@comment-24531362-20150219192237

So, ready for a theory?

I postulate that Ukitake either has no Bankai, or that his sacrifice through Kamikake is his Bankai. Might it be possible that his rank as Captain was granted as a result of both his uniquely powerful Shikai and his importance to the stability of the universe, and that he, Yamamoto, and Shunsui (the three who were likely to know about Kamikake) had bluffed about his Bankai to dissuade attempts on his life? Or that, if Kamikake is Bankai, he couldn't use it before the proper time a la A-The Almighty because it only unsealed in times of the Soul King's greatest need and costs him his life in recompense?