User blog comment:Xilinoc/Ch. 545 - Blue Stripes/@comment-1268838-20130709151049/@comment-8295743-20130709175827

One of the character books, I think SOULs, explicitly states the shihakushou was created by Yamamoto. As far as we know, the uniform is simply that, a uniform. But then again, this whole headache of an arc has been about Kubo violating just about everything he established in the past 10 years or so(I forget how old the manga is)