Rean wasn't the only one acting at that moment. Kentucky and Celis each went to one of the Sea Demon Beast powers to play the same thing. They followed the same strategy as Rean. They didn't buy a fight with anyone.
Instead, they offered something that the leaders of those powers simply couldn't refuse. Obviously, a Celestial Stone each. As mentioned before, they received a few from Dofrei, thirty, to be more specific. There were five controlling powers in this Ocean, and considering that the prize was Hyeoumu's real body, it was worth the investment.
One might be thinking, what if the one who finds Hyeoumu's real body decides to not speak about it? Well, the twins' group tried to resolve it. One of the things the twins' group did as they gained the support of the five powers was to offer an impossible-to-refuse reward to anyone who found the right turtle.
