For Us?
Hashirama was right.
It is selfish to bring back the dead.
He was shelving Impure World Reincarnation. This would be an experiment that he wouldn't finish. And it was better that way.
Itama and Kawarama were returned to the Pure Land.
There were other experiments to work on. He will continue with his experiments, he would make more breakthroughs, but no more necromancy. Just because he was the man who could bring back the dead, doesn't mean he wanted to be that. He definitely didn't want to be, not after how Hashirama had reacted.
A shift in focus was a welcome distraction.
Self experimentation was always an option on the table. It was a good distraction from sinking guilt he felt. And besides, he needed to check on the cells he had inserted into himself.
Outwardly, there was no affect on his left arm. He didn't know if this was a good thing or bad thing. Did he need to input more of his brother's cells?
But he did seem to look and feel younger, that's something he had noted. Was this a side effect as a result of his experiment or did it have a different cause?
Was he able to use wood release like his elder brother? He wanted to know. There was only one way to find out.
Tobirama had always wanted to be able to use Wood Release like his older brother. Ever since his older brother had first discovered it, Tobirama felt a tinge of jealousy towards his older brother. He tried to preform wood release but he couldn't. He just couldn't.
Just another way he wasn't like his older brother.
He was born with silver white hair and icy blue eyes. He stood out. He was the odd one out. It was only until Itama was born with half of his hair silver white like his and one icy blue eye. The child validated his existence, that he was his father's son.
Even with his existence validated, he still was a tiny bit jealous of Hashirama.
And that was why he started this experiment, even if he didn't want to admit it to himself.