After Shang left the Isolation Barrier, he noticed that Linay had left.
That made Shang realize that the time for which he had booked her had passed.
Shang was now alone again.
As Shang looked at the surrounding Eternal Ocean, he felt that he wasn't safe enough.
Sure, he had an Isolation Barrier made by a Mage King, two powerful Isolation Chambers, a direct line to every member of the Lightning Manor, and a pin with which he could contact the Lightning Emperor, but there was still something that could happen to him.
If Shang decided to leave the Isolation Barrier, like now, a powerful Mage Lord could theoretically stand at the ready to ambush him.
Shang would only feel safe when all of this was covered.
Eventually, Shang called Linay again.
"Hello, Shang," she answered.
