This battle was dumb why would Obito take Kakashi to the kamui world and fight him fair? The reason Obito is so powerful is because he's untouchable and knows lots of forbidden justsus. Kakashi is far better than Obito at fighting especially since he fights fair and has way more experience, Obito just stays intangible and usually runs away. I don't know why he thought he could take Kakashi but he did and he failed.
This battle had so much potential but Kishi kept it short and simple.
This battle had so much potential but Kishi kept it short and simple.