Reviving Hashirama Senju!

While Madara Uchiha faced off against Ōtsutsuki Isshiki, who had been lurking in the shadows, Uchiha Ensei was hiding in the Kamui Dimension, studying the Rinnegan's abilities.

The Rinnegan Madara Uchiha had given him happened to house Rinne Rebirth.

Honestly, this ocular technique wasn't much use to Madara Uchiha.

After all, it consumed the user's own life force to resurrect others. Very few people could bring themselves to trade their life for someone else's.

But to Uchiha Ensei, life had a price: a little over three million ryō.

For less than a tenth of an Asuma, he could produce a spare clone specialized in life force.

Although a body like that couldn't truly meet the Rinnegan's demands, it could hold out for a few dozen minutes without trouble.

As long as it could cast Rinne Rebirth within that brief window, that was enough.

"Rinne Rebirth! A jutsu that can resurrect the dead with almost no restrictions. It really does make me curious."

"Should I revive Hashirama Senju and have him fight Madara Uchiha?"

"Hashirama Senju probably couldn't beat Madara Uchiha as he is now."

Uchiha Ensei had already put his own eyes back in. Looking at the Rinnegan in the clone before him, he sank into thought.

Rinne Rebirth was indeed a broken ocular technique. In the original story, Nagato had used it to revive everyone killed in battle in Konoha, and Madara Uchiha had also relied on it to return to life.

But aside from resurrection, the jutsu didn't have much use.

No wonder Limbo: Border Jail had been the only Rinnegan ocular technique Madara Uchiha used from beginning to end. As for why he hadn't used his Mangekyō Sharingan's ocular techniques...

Of course, it was because Madara Uchiha's Rinnegan couldn't actually revert to the Mangekyō Sharingan at will.