First, if we make a big show, the Whale Emperor would first become vigilant. If there are any means of communication, the Underworld would preemptively defend, which would be disadvantageous to us, leading to a passive situation.
Second, we ultimately need to guard both north and south, and cannot focus solely on one area.
Third, once the number of combatants exceeds, it becomes difficult to retreat. With three or four people, it's easier to manage the battle; with ten, if one person falters and becomes ensnared, won't others try to save them? If they do try to save, it would be easy to start a chain reaction of getting bogged down.
Fourth, we are aware of the situation and understand that an unprecedented great change in ten thousand years is upon us. The Holy Emperor has the courage and determination, with the arrow already on the string, having no choice but to fire first to gain the upper hand.
