User blog comment:Xilinoc/Ch. 616 - Mimihagi-sama/@comment-24531362-20150219192237/@comment-24153155-20150219222650

I also believe that Ukitake must have some sort of Bankai (No more Kenpachi nut cases, please ;), but I don't believe Kamikake is his Bankai. Aside from Ukitake being ill most of the time, it actually makes sense that he often doesn't actively engage in fighting until no other options are available now we know about Kamikake. I think his actual Bankai might be very tricky to handle given his health. Somehow it also feels Kamikake is not Ukitake's per se, as is the case with Shikai and Bankai, but rather he happens to be the soul who "simply" can perform Kamikake due to his history.

Given that the translations were okay this week, it could very well be that Ukitake's body had to "cure" to be able to pull off Kamikake. I think it's rather interesting that it is him who can actually decide it is time to give his life, instead of the Soul King deciding for him (kinda like Yhwach and his Quincy). It all suggests that someone/something really thought about how to protect (the balance).