User blog comment:Xilinoc/Ch. 579 - THE UNDEAD 6/@comment-1268838-20140507172539/@comment-1268838-20140507195126

Granted, that Unohana is alive at all is speculation, but I know Kubo loves his double meanings for chapter names. She could be only figuratively dead (her Kenpachi self), hence "undead." As for her relationship to Isane, I am pretty sure that was genuine. She seemed more reluctant to go crazy again, than anything. I think she might have softened up, but went back to her old self out of necessity.