――Every Day is Summer Vacation – Strongest and Richest Before He Knew It!

A world where dungeons suddenly appeared in various places.

Japan is no exception; several large dungeons exist in each prefecture.

In dungeons, magic stones—an unknown energy source—and never-before-seen materials can be gathered. As such, all those with talent eagerly became 【Explorers】 and amassed their fortunes.

Meanwhile, the protagonist, Koichi Natsume, had no notable talent recognized even in the national dungeon aptitude test. Longing to become an Explorer, he spent his days working as a corporate drone.

What's more, perhaps due to his clumsy personality, he ended up getting fired from his company.

Returning to his family home in the depths of despair, he happened to peek into his childhood secret mountain base, only to find a shimmering, writhing dungeon gate had appeared there.

Inside the dungeon gate, a summer vacation mountain, echoing with the cries of cicadas, stretched out. Even though it was winter outside, the sense of season seemed to be glitching.

Although government inspection certified it as a "mere space" with no monsters or items, in reality, that wasn't the case—.

Through self-improvement in his private dungeon and repeated challenges to urban dungeons, Natsume becomes famous and accumulates wealth.

※Also published on Kakuyomu.