Just before you start reading this, there is a bit of a spoiler from Metal Gear Solid V: The Phantom Pain, below. However this is rather important, so at the risk of spoiling the game, we’d rather save you some grief. Alright?
Looks like once you acquire the bikini wearing sniper, Quiet, in Metal Gear Solid V: The Phantom Pain, that you can have her accompany you in missions. However per Konami, if she is used as a buddy in specific missions, mission 29 and mission 42, she can cause the game to bug out and corrupt your game saves. Yes, completely corrupt your game saves and it affects all platforms, so no one is safe. This comes directly from Konami’s support page which can access here.
“Regarding game progress being stopped in “METAL GEAR SOLID V: THE PHANTOM PAIN” under specific circumstances. In “METAL GEAR SOLID V: THE PHANTOM PAIN” which was released on September 1st, 2015 there is a possibility that the game stops progress if having Quiet as a buddy while playing “Mission 29” or “Mission 42”. This situation can be avoided by not using Quiet as a buddy while playing either “Mission 29” or “Mission 42″. We deeply apologize, and appreciate your patience for further announcements regarding this issue. This issue is known to be present for Xbox360, XboxOne, PlayStation®3, PlayStation®4 and Steam.”
Obviously this is a big deal and I’d imagine that Konami is hard at work on patch to address this, or at least I hope they are at the very least. In the meanwhile, make sure that you don’t take Quiet out on any moonlight sniper sprees with mission 29 or 42. Besides, DD, would rather hang out with you instead.