Facing a dead end, Nishida was forced to reveal the confidential information that there was someone leading him behind the scenes.
He divulged this situation with a troubled heart, afraid of being killed by the person behind the scenes. He was utterly terrified, but to handle the crisis at hand, he had no choice but to speak. If he didn't, there was a possibility of immediate death.
To handle the current predicament, he had to make some sacrifices. What happened afterward was up to fate. With that mindset, he realized he had no other way out beyond this.
Peng Bird, Flower Snake, Hua Diao, and Mountain Ghost saw Nishida's earnestness and believed he was not faking it.
It could be understood that there was someone leading Nishida from behind, and it was also understandable that the second map fragment was in this person's hands. It made sense for two groups, one in the open and one in the shadows, to each watch over a map fragment.
