Kojima studios are hard at work on two of their own games, and helping with Castlevania among other projects. We alredy mentioned this in the ZOE3 article, but one thing we left out is how Kojima is not "directing" any of these titles. He has little to no help with any of the current projects, but it seems that its because he is working on his own mystery.
Yes according the latest Famitsu interview, Kojima has a secret project of his own. So far all we know is its "better than Peace Walker" and in development for consoles. This is exciting for us MGS fans as most of the "hints" are pointing towards a Metal Gear Solid 5, no not another Rising, a true MGS title.
Why? Well Kojima noted "the engine is already working" also stating that the engine is taking technological advances with the team. He then stated "We'll be doing things that we couldn't do in Peace Walker." Remember the Peace Walker making its way to PS3 rumors?
Just remember MGS is a rumor for now, Kojima has yet to state if its something original or a sequal/remake of any kind.