User blog comment:Godisme/Everything But The Rain Op. 2 "The Rudiments"/@comment-4794735-20130306172742/@comment-1393830-20130306173013

Nimaiya stated that Ichigo created his Zanpakuto without an Asauichi a chapter or two ago. Urahara explained how he did it pretty early on in the series. He solidified his reiatsu into the form of a sword, thus creating a Zanpakuto,