Board Thread:Questions and Answers/@comment-9826910-20130618064245/@comment-11063250-20130619211029

Zangetsu is the name of Ichigo's soul. If Juha Bach shadow and Hollow Ichi are both in his soul, then they are both Zangetsu. Inner turmoil can always cause conflict in your soul, the resolution between the two sides has increased Ichigo's power exponentially.