Board Thread:General Discussion/@comment-3244769-20140121195139/@comment-24282510-20140121215717

Litwos wrote: If renji got a new Asauchi, why is still Zabimaru his zanpakuto? Shouldn't it change?

No Zabimaru is his zanpakuto spirit that is born with him and will die with him.

A asauchi is more or less a medium for that spirit to help the said shinigami, in fighting hollows.

Remember Tōshirō Hitsugaya saw his zanpakuto spirit "Hyōrinmaru " long before he became a Shinigami.