User blog comment:Hissatsu/just ask/@comment-1705035-20130920090337

SS1 Originally release in DVD Format and has BD relase later. And I never see the package of BD SS1 on any site (include animate). So I think it's hard to find SS1 in BD Format.

SS2 and onward have the same release date for both BD/DVD. These would be easy to find. After searching, I see play-asia and CDjapan can still cover all SS2/SS3 BD with limited edition. Also BD of OVA, BD of Movies and DVD of SS1.