The revival fluid.

The ratio needed is 30% nitric acid to 70% alcohol and the reaction won't occur unless it's perfect. However what if this was not the case though. What if there was a reaction before this magic number was reached along with several other things that could have been known at the time. That something happened in the past whenever the Medusa was created that allowed for this golden ratio not to be the absolute that was required but just one possibility that could cause a reaction to an accordingly.

That this one change in the past had a butterfly effect on the future as things that should have happened as result never would. While other things that never happened at all do happen as instead. For one thing, the lions that were in various zoos never were able to escape their cages. Thus with the lions not being able to go back into the wild and they never readjust to their new environment. Instead, they all just died out unable to leave their cages. Though the chances of every lion from every zoo being unable to escape from their cages somehow were unlikely it was impossible though. It just so happened this was the scenario that happened allow for them to be never introduced into the wild.

What role would this play in the story well without the lions escaping to roam around and live out in the wilds that Japan would become over time? There was no real need to use the revival fluid on Tsukasa at all. The only reason it seemed like it was used on him in the first place was not that they even wanted him around. They need someone to help them out of a jam thus he was chosen over Yuzurhia as result.

However, if there were no lions to prompt them then why would they ever use it on him. Having found the world's strongest primate would have merely been something that happened and nothing more. Taiju nor Senku would have used it on him as it would not make sense after all. He was not their friend and they did not even know him merely knew of him. So why would they pick him over Yuzuriha who they traveled out there to get in the first place?

The answer most likely would be they would not thus Yuzuriha would be carried back towards the treehouse where the two of them were staying at the moment. Clothing would be created for her as that would be how the thing would go down starting from there.

Not understanding why she would even need them in the first place as she had been naked on that tree for thousands of years after all. Sure they were only too well the only two humans that probably saw her but still. Hopefully, this does not get absorbed into her clothes and the smell gets stuck in them Senku though.

Thus it was poured over Yuzuriha's head and the two just watched and waited for them the revival fluid to go about doing it things. They had already tested it once on sallows that were also petrified along with them all those years ago. Though the question of why was it just the sallows that were affected and seemingly no other animal at all. Most interesting enough why were other primates not affected as it would make more sense that they would be affected more than a certain type of bird.

Regardless the fluid worked and Yuzuriha was brought back as the third person to be reverted from their petrified state to Senku's knowledge. Since there was no Tsukasa around there was no rush to do anything as things were taken at their own pace. Senku left the two alone for a while to do some catching up since they had spoken to each other for nearly four thousand years after all.

After all while just telling her about all the things that he and Senku had been doing since Senku had first reverted himself. It had become later it was time to start on their dinner which Yuzuriha wanted to help with. Already eager to lean a helping hand towards her friend.

She went off to go gather some things to help make a fire however after the sun had gone down and she still had come back yet. The two then went after her only to find that Yuzuriha did indeed find a bunch of things to help start a fire with. However, the reason she never came back with these things was that she had reverted into a statue. Seemingly after the sun had gone back and it had gotten dark out.

Luckily for them, it was not that dark that they were not able to bring her back to the treehouse where they were wondering what went wrong as the formula should have worked as it did on the sallow they tested in on. Although upon getting back they discovered that a very small sallow had fallen from the sky. By sheer chance managed to land safely without being shattered into piece after dropping for being in mid flight.