In Order to Become an Immortal, I Killed the System

The protagonist has immortal abilities + mental madness + a slightly sagging plot Lu Li traveled to another world. Lu Li got a system and climbed up the fairy mountain with the help of the system. The door to immortality stood on the top of the mountain, but Lu Li could not cross it. It was he who became immortal, not his system. So, he killed the system and returned to reality. The system died, but he gained the ability to be immortal. He also discovered that his world was not as peaceful as it seemed. In order to become an immortal again, he began to travel to various dangerous places. What others see as a place where he must die is the place he flocks to. Facing the huge monster, the others were trembling unspeakably. Only Lu Li was slowly walking toward him. "A magical creature with such a structure must be helpful for me to become an immortal." This novel and its characters are purely fictitious. Any similarity is purely coincidental and should not be imitated.