[Machine Translation] Fuyuka and Haruka decide to travel to the U.S. to obtain strategies from an American mercenary group in order to defeat the flying dragon Rimdobmul. First, they set out on a journey across Japan in search of their missing father, Shiki, in order to obtain passports. After visiting dungeons all over the country, they finally reunite with their father, who is harboring a secret that neither of them could have imagined... Suddenly, the "Stampede," a monster overflow that has been occurring in dungeons all over the world, plunges the entire planet into chaos. As the entire planet falls into chaos, two of Japan's strongest men decide to become "Heroes in the Shadows" and head for the Tokyo Dungeon to defeat the monsters that are overflowing onto the surface of the earth. There, however, the siblings witness a horrifying truth. The war between mankind and monsters is about to begin. The second volume of the siblings' fast-paced dungeon warriors' story is about to undergo a drastic change!