The four rulers that the Celestials were referring to were the wolves that Shin was eyeing.
Yes, the four wolf brothers, earlier five but now four since Kira is thought to be dead, arrived at the scene.
They were attending the event as well so it was normal for them to come. Of course, a major reason why Shin came to the place was for them.
Aella, whose body was shaking with anger and fear, couldn't wait until she could get her revenge.
The reason for anger was simple, and the reason for fear was because of the immense aura that surrounded them.
There were six wolf brothers in total:
1] Devis
2] Lurion
3] Kira
4] Freris
5] Aaron
6] Gargus
These six wolves had a characteristic of their own and were famous throughout the continent. Every race knew about them and there was no one that didn't fear them.