He failed, his plan to use the Ten Tails to bring peace to the world failed. As soon as he finished his last words to Hashirama he died. Again. He was expecting the next world to bring him some kind of peace, but instead...
"Wah!"
"It's a boy!"
What... Even...
Apparently the universe wasn't finished with him yet. Huh. Why was he a baby though? That was annoying. Not something that he couldn't deal with though. All he had to do was act like a normal child until he was strong enough to take care of himself. How hard could it be?
The doctors placed him next to his mother. She, to his undeveloped baby eyes, appeared to be identical to his real mother. Not that he could remember his first birth. He simply didn't think they had this kind of medical equipment back in his day. It looked even more technologically advanced than what the world currently had. Was he in the future then? Who knows. He was tired. He'd just fought the battle of the millennium, died, then was reborn. He'd think about it later. For now he simply wanted to sleep.
Fourteen years later...
Madara had learned a great deal about this world since he had been reborn. It was nothing like his old one. Even the shape of the countries that covered it were different. None of the landmasses were the same. Moreover there were hundreds of different languages. There wasn't any ninja or even samurai. Instead "heroes" were everywhere, doing jobs that ninja should have taken care of. These heroes were vastly limited in their effectiveness by their inability to use chakra. Instead each of them possessed a single power, called a quirk, which determined their strength.
"How absurd." he found himself thinking over and over. The only thing this world seemed to have going for it was the technology. The fact that he could carry a computer in his pocket was incredible. He had a hard time understanding how a world full of idiots could produce such amazing technology. How could they have invented so much when they don't even know that chakra existed?
It wasn't as if they were incapable of using it. He'd experimented a bit. Feeding his chakra into small insects that were still developing in a manner similar to the Aburame clan. The insects didn't die or get sick. Instead they absorbed it, became more intelligent, and wouldn't leave him the fuck alone after that. He'd ended up having to kill them just to get them to stop following him. Which was a shame. He'd enjoyed playing with them. Such was life, as it was. As for himself he was pretending to be quirkless. However his skill had not diminished at all. Only his chakra levels and control had been affected. Now that he was entering adolescence, his power was growing back to an acceptable level. Soon he'd reveal his power, by becoming the first quirkless person to pass the UA entrance exam. Then the real fun began.