Board Thread:Improvements and Issues/@comment-1409915-20140307195609/@comment-8986886-20150605180202

NotARobot9181 wrote: Even during the anime filler where the Zanpakutō take their humanoid forms, Two people stand out because their Zanpakutō do NOT do this. Kenpachi and Yachiru, people shrug off Kenpachi because he was never able to use Bankai, but no one mentions Yachiru at all during this, which could just be a fluke, or on purpose, even though it was filler, it could give some nudges towards that Yachiru was Kenpachi's Zanpakutō.

Kenpachi, and Yachiru, were away on some mission to exterminate Hollows during the first half of the arc, and thus weren't affected by Muramasa's hypnosis. It's that simple really, and in a scenario where they  hadn't been absent , the fact that Yachiru  didn't turn on Kenpachi  would only prove that she  isn't his Zanpakutou , because all the other Zanpakutou turned on their Shinigami masters.