User blog comment:Apocaylpse06/Ichigo Kurosaki's (New) Zanpakuto/@comment-3010659-20110817104256/@comment-44061-20110817155753

Actually it could be isshin's shikai we didnt state it on the page cause we dont really know. We assume it was sealed but some zanpakuto dont have to change form in either shikai or bankai. This simply a physical change that is unique to varying zanpakuto