Board Thread:General Discussion/@comment-4957813-20131130185522/@comment-5553481-20140604121029

Benter wrote:

Katen Kyōkotsu and Sōgyo no Kotowari manifest them self as 2 separate spirits. Hisagi's zanpakuto has only one spirit. For the latest version of Zangetsu it is unknown. As far as I know, they "show" themselves as 2 separate entities, but they're still one spirit, while Ichigo's blades are 2 different spirits ("Hollow" Zangetsu and "Quincy" Zangetsu)