After a series of tests, Su Xiao discovered that there was indeed no way to enter the purple-black semiliquid. He had tried everything, from holding a fragment of the scroll to entering spatial penetration, but none of it worked.
This made Su Xiao marvel at Guy's ability to cling to life. The purple-black semiliquid was so troublesome, yet that fellow had used his own abilities to help a not-particularly-powerful Alchemical Creature crawl onto the roof.
After Su Xiao stuck his finger into the purple-black semiliquid, the first 0.5 seconds brought excruciating pain. After that, it went numb. The feeling of his finger about to be broken down and scoured into inorganic matter was awful.
He moved the little finger of his left hand, and the discomfort gradually faded. Su Xiao walked toward the metal cover on the roof. After opening it, he climbed down into the Shelter Hall with Bubu Wang, A'Mu, Baja, and Benny following one after another.
There was still no one in the Shelter Hall. Su Xiao arrived in front of Room 7, took out a sheet of paper, and wrote: "There's nothing I can do."
After writing this, he pushed the paper under the crack beneath the door. Before long, Guy replied from inside. Su Xiao and Guy began negotiating through this method, as follows:
Guy: "My dear friend, you can't abandon Guy. Have you forgotten the friendship between us in the Devil Sea World? You must find the key to Room 7."
Su Xiao: "I'm powerless to help."
Guy: "My dear friend, after this is done, the reward will be 5,000 (messily crossed out)...4,001 Soul Coins."
When he saw this, Su Xiao's expression showed a moment of surprise. He had known Guy for so long, and leaving aside Soul Coins, the man had never even