Twenty years ago, a dungeon appeared in Hachioji City. Eiji Aikawa, the ‘Swordless Hero’ who defeated the final boss and unlocked the dungeon where unknown resources lay, hid his achievements and worked as a corporate drone for a subcontractor under Japan Dungeon, Inc. Despite being S-rank, he lacked the privilege of carrying a sword, which…

After being discharged from military service, dreaming of a comfortable life, the protagonist gets a job at an academy. However, too many incidents keep occurring at the academy.