User blog comment:Marijuanna/Visard before Turn back arc/@comment-8464927-20130827062524

Well the Visored are a group of shinigami(Shinji,Rojuro, Kensei, Lisa, Love, Hachi, Hiyori) who were infected/became hollows due to the work of Sosuke on that night. Any other possible shinigami that can don hollow mask wouldn't be considered a Visored unless they were invited to the clique. But back to the question, it really would be unknown if it has happened before since they stated that it was prohibited. I would say no, since usually rules are meant to keep things in order and having a hollow/shinigami hybrid would just be outrageous. If someone did perform the process of hollowfication I wouldn't be able to say who because I don't know, but I have a feeling it was a failed experiment if such process did occur.