Kamui's Dimension

The is an alternate space that is linked to Obito Uchiha's Sharingan. Kakashi Hatake's Kamui and Tobi's Space–Time Migration share this same dimension when teleporting objects, due to the fact that each has one of Obito's eyes. This is further evidenced by the fact that objects warped by the former ability were still able to interact with Tobi despite his otherwise comprehensive "intangibility". Prior to learning the reason of this connection, Kakashi exploited it to injure Tobi during the Fourth Shinobi World War.

Due to the Space-Time Migration and Kamui being the only two known pathways into and out of this dimension, there seems to be no other way of escaping it.

Appearance
The location was first observed once Tobi transported both Sasuke Uchiha and Karin there after their battle at the Five Kage Summit, where it was shown to be composed from an innumerable amount of randomly arranged and differently sized rectangular prisms.