JK Musou - Owaru Sekai no Sukuikata

Summary

Creatures that were supposed to exist only in fiction were running rampant throughout the world, drawing civilization close to its demise. That day, I, the protagonist, noticed that there was a special skill dwelling within me. Leveling up the more she fights and gaining new skills as well as the ability to harness magic in turn, a high school girl who was once a shut-in was integrated into a group of people the system labels as "players." She makes the decision to exterminate the monsters and save the people around her, enjoying the laid-back life the end of the world has brought her all the while.