Hashirama Senju had once thought Sage Art: Wood Release: True Several Thousand Hands was powerful enough. Its Buddha statue stood over a thousand meters tall, a terrifying sight, and the Ninjutsu could only be used at the cost of his life.
Back then, he had used Sage Art: Wood Release: True Several Thousand Hands to defeat Madara Uchiha and the Nine-Tails.
Yet the Susanoo Uchiha Yi had used stood roughly a thousand meters tall, about the same size as his True Several Thousand Hands.
And Yi had wielded Susanoo without the slightest strain. Clearly, he could summon one on that scale whenever he pleased.
Yi was plainly stronger than Hashirama and the Madara of those days.
"We can still help in some way." Yi shook his head slightly. "The Impure World Reincarnation Jutsu can still be improved so the reincarnated can use as much of their former strength as possible. And I have plenty of experimental subjects. White Zetsu would make the best vessels."
Yi thought of Orochimaru again. He would still need Orochimaru's help with the human experiments to come. With Konoha's steady supply of resources, Ōtsutsuki cells, White Zetsu bodies, the theoretical knowledge Yi could provide, and Tobirama Senju's cooperation, he was genuinely curious how far they could go.
If it would help Uchiha Mikoto and Kushina Uzumaki, Yi wouldn't mind contributing his own cells.
As for money, weren't the Daimyō still around? They could keep draining the entire Shinobi World if need be.
"Fine!" Tobirama agreed without hesitation.
He hadn't planned to return straight to the Pure Land anyway. Now that he was back in the Shinobi World, he had to do something. Besides, Madara Uchiha was still alive. How could Tobirama be dead while he lived?
Seeing Tobirama agree, Hashirama sighed softly and gave his consent