Board Thread:General Discussion/@comment-4976518-20140808063123/@comment-26912075-20180113203517

That's wrong. When Aizen released his zanpakuto in the Soul Society Arc he specifically used a release command, which is characteristic of a Shikai. If it was his Bankai, he would've said "Bankai, Kyoka Suigetsu" instead of "Shatter, Kyoka Suigetsu". Kyoka Suigetsu is also a phrase in China (not by that exact name of course). That hints that Kubo clearly meant for those two words in conjunction and never separately.