The Secret of Spiritual Energy Recovery

The recovery of spiritual energy is not as beautiful as expected. Ferocious beasts are far more sensitive to changes in the surrounding environment than humans. In the early stages of recovery of spiritual energy, humans were forced to rely on huge city walls to survive. Are these huge bases really built to protect humans? When an ordinary man from the earth obtains a system that allows him to gain power points by killing monsters, and resolutely walks out of the base, what kind of ending is waiting for him...? This novel and its characters are purely fictitious. Any similarity is purely coincidental and should not be imitated.