C599 Where Is This

That jet black fog followed behind Zuo Feng like a ghost. The black mist did not stop at all and entered the mist. The same mist did not seem to have any effect on him.

However, not long after they entered the mist, a surprised "hmm?" sound came from the black mist. This sound was very weak and seemed to be uncontrollably made. Then, it was immediately retracted