Back in the trial ground: Raya's side...
While her reaction was even more exaggerated than Muku's, it didn't last too long. Not because she adapted to the pain quickly. No, it was because the weird energy in her body acted faster than Muku's.
So, after a little while, the pain began decreasing to levels she could tolerate. It still hurt a lot despite that. She didn't open her eyes once throughout the whole process.
Fortunately for her, it took her around half the time it took Muku to gain complete resistance to that level of flames.
This highlighted the advantages of beasts, especially those like Raya, over even the most talented humans like Muku.
It seems even with cheats, there were some things which were just insurmountable. At least for the time being, without their bloodline and any buffs, Raya was way ahead of him.