Elle's Quest! Yuusha Elvira wa Genjitsu Sekai ni Ten-ishimashita

Mashiro Mizuki, who works part-time at a video game store, starts up a mysterious second-hand game disk. What appears is Elvira, the hero of the game! Elvira tries to get back to her world with a teleportation spell, but in the real world her experience has been reset back to Level 1, and she is unable to cast the powerful spell. Now Elvira, the former hero, will help out at the game store to gain real-life experience and level back up.

(Source: Manga Time Kirara, translated)