While battling with Tobi, I have seen ninjas getting teleported to a place, which is kind of a dark room, having floor made up of blocks.
Is it a real place like a cave somewhere far? Or is it Tobi's subconscious mind?
Justification is required when considering a fighting scene between Tobi and Kakashi-Naruto.
When Kakashi is teleported into that place, Kakashi counter attacks with Kamui making Tobi bleed (cough blood). And Kakashi manages to return back to battle field.