I think that Kabutomaru is when Sasuke killed Orochimaru and Kabuto use this..I forgot of Orochimaru, and now Kabuto's half or one of his eyes looks like Orochimaru. So like I think that Orochimaru is half of Kabuto and he's planning evil things.
Hopes this helps. I know I suck.
I predict it might be Madara's brother but it is just a prediction so dont get mad if I get it wrong.
of course but the game only lets you play as naruto sasuke and kabutomaru so it suck so dont buy foo. thanks but you can be a whole bunch of people in it like 40+