I dunno... at first I thought it might have been because I bought both "School Mate" and "Artificial Girl 3" games through them @ $100 each, so I thought it was like a "thank you" for all the $$$ I've sent their way. (I've torrented enough Illusion games in the past and felt it was time to pay them for their hard work.)
But then my friend bought his 3 Higurashi CDs getting the calendar as well, and I think it was the first time he'd bought through them, so I *think* it must be if you order all three official Higurashi CDs at once. That seems to be the common denominator
