Cytuj:
Black Curtain/黒幕/kuromaku
literally Black Curtain but the meaning is Yondaime is talking about the one who is REALLY in control of Akatsuki. the manipulative masked man behind the scenes... Madara. "Black Curtain" is a figurative phrase in Japanese language, but I have translated literally because the cover seems to show two masked Madaras who are wearing a cloak that looks like a black curtain.
And finally this is just my opinion but it seems like an organisation above Akatsuki is being introduced called Kuromaku. Just think who are the members, probably Danzou and other old people ;-)
Disclaimer: if the word 黒幕 was only used by the spoiler writer but not Kishimoto then this theory completely fails :P
Swoją drogą widok Minato który dostaje hita od Naruto jest piękny ^_^