This is とらのあな限定特典 設定資料ラフ集, that is Toranoana Limited/Privileged access Content creation material rough set (lousy translated).
That means, it's additional material (work-in-progress sketches and so on) produced by the creator(s) of the manga while working on it, but not for publication; then made available only to those who (presumably) paid for the Vip access or such additional material (somewhat likewise the separate cutted/alternative scenes add-ons on film DVDs).
cgc is right in getting angry, imho, but everyone should remember that sometimes is just a matter of misunderstandings and people not knowing what is what, on top of the problems of foreign languages.
@cgc Since it appears you can write well enough in english, I'd suggest you to include an english-translated title in your galleries. This could prevent some unwarranted critics