Board Thread:General Discussion/@comment-24317446-20160321225110/@comment-1387259-20160321231500

This is a viable theory. Unfortunately it boils down to the fact that we may never know the correct answer, unless we see Aizen do something hinting at it (all he's done so far is use a 90's-level Hado, which doesn't tell us much). Basically, we have Urahara's claim vs. Aizen's claim. Kubo never really did hint at which one was actually correct.