Ghost Emperor Midu and numerous Ghost Kings have been "patrolling" the Immortal Realm for a year now.
This was a task assigned by Zhang Yang for them to cooperate with, where they only needed to patrol the outskirts of the Immortal Realm and then return.
Each time, they could feel the Ghost Realm growing stronger, so they willingly cooperated.
This time, after another patrol outside the Immortal Realm, they were supposed to prepare to return.