世界中に突如現れた無数の洞窟。そしてそこに棲む謎の生き物たち。
各国政府はその「ダンジョン」を調査・管理すべく総力をあげて取り組んでいた。
そんな中、貧乏ふたり暮らしの兄妹、冬佳と春香が住むボロ家の地下に、突然現れた新たなるダンジョン！
ふたりはモンスターがドロップするというお宝や肉を目当てに、自分たちだけでこのダンジョンを探検し始めるが…
Countless caves that suddenly appeared all over the world. And the mysterious creatures that live there.
The governments of each country were making every effort to investigate and manage the “dungeon”.
Meanwhile, a new dungeon suddenly appeared in the basement of the Boro family where the two poor brothers and sisters Fuyuka and Haruka live!
The two begin exploring this dungeon on their own, looking for the treasure and meat that monsters will drop …
