Once Upon a Time, the "No Blade" in Last Dungeon.

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 led to occasional scorn. Still, he carried out his duties without complaint.

One day, Mii, the niece of a former comrade, approached him, asking to be his disciple.

“Please, old man! Do dungeon streams with me!”

Eiji agreed under the condition that it would be a one-time thing. However, upon returning to his former battlefield, he saw that it had become nothing more than a playground for corrupt elites and a den of dirty money-making schemes.

“A dungeon isn’t your playground. It’s not some filthy business venture, either.”

This is the story of a former hero, now hiding his past, who unintentionally finds himself in the spotlight again as he coaches a group of middle school girls on their adventures.