C672 Hidden from the Heavens

It was the morning when Shi Lei ran back from the outside. Just as he was about to go home, he saw a letter placed at the door before he could open the door.

Shi Lei looked around and did not find anyone wandering around his room.

But because of his curiosity, Shi Lei opened the envelope and opened the letter inside.

The three words "letter of challenge" appeared at the top of the letter