"If a mortal use demonic energy without a contract with a demonic being slowly their mind and body will get corrupted."

"Like that guy Ren Hector. He had a contract with a demonic being. But he took external access to that energy and demonified. Also died at your hands."

"Wait you mean? Did he meet a demon? Demons are already on earth?" Hearing this Shin was worried. If it's true. It's too dangerous.