Song Nianchu waited until everyone else had entered the Secret Realm before she and her group stepped into the Formation.
Different sectors are reached via different portal Formations. While the arrival times differ, there is still a chance of encountering others once inside. However, since the interior is vast, crossing paths is purely a matter of luck.
Xia Zhiqian and his companions had never entered the Demon-Subduing Secret Realm before and were unfamiliar with the environment. Upon entering the perimeter, they immediately felt a sense of unease.
Chapter 961