As I recall this cel was originally sold by 
mandarake a while ago.  And I believe has passed 
thought the hands of a few people.

When Mandarake was selling it they advertised it 
as a hanken cel used for the cover of a 
doujinshi.  Meaning that although it is a hanken 
it is an illegal hanken and thus did not have 
any legal copyright status with it.

So you may say it is a real hanken made by a fan 
(or a pervert depending on your viewpoint).