Strongest Behind Walls

Time traveler Sylas awakens as a C-class warrior, bound to the "Strongest Guardian" system - leveling up every second, at the cost of being unable to leave Shelter Town for life. He is willing to live a low-key life, but is publicly humiliated and despised by SSS-level geniuses. It wasn't until the army of monsters approached that he drew his sword and killed the whole field with one strike. However, the real trouble has just begun: the Abyss Lord awakens, the demons are attacking, and the power of the Creation Source in his body is about to lose control... and he is still trapped within the boundary of the town, unable to move an inch.