Kamui is a realm made by the gods.

(Or so Madara said. Obito was inclined to believe in him.

Madara had looked at him with a cold gleam in his eyes that was far more pleasant than his usual gaze and a part of Obito flocked to that like a man starving to a scrappy meal.

'It 's a good ability, ' Madara said slowly. Obito, having thought it was kind of lame compared to eternal fire and whatnot, immediately nodded. Feeling something like heart palpations. 'It 's very useful. '

You 're very useful.

Was the implied meaning.

Obito didn 't mean to smile, he really didn 't. Kamui was gotten from Rin 's death, after all. That terrible, bloody day entrenched into his mind and refusing to leave his waking and resting moments alone and just-

He smiled, nonetheless. Like a simpering fool as Madara gave him the first praise of few.)