Originally Posted by AniMeFaN

I suppose we may know soon enough what is going on but here are some interesting panels.

http://www.mangahere.com/manga/naruto/v58/c550/9.html

First panel Kabuto is claiming its "his eye", theres only one genjutsu strong enough to do this.

http://www.mangahere.com/manga/naruto/v58/c550/13.html

Second panel Kabuto finds out that the eye actually belongs to Shisui and its his Koto amatsukami.