The bidding has begun for the Otherworldly Language Comprehension skill orb, which threatens to rewrite Earth's political balance by revealing the contents of the mysterious messages written on dungeon geometry! This draws the attention of the world's superpowers, and mysterious "neighbors" begin moving into the nearby houses. Meanwhile, Keigo and Miyoshi's avaricious adventures take them deeper into the dungeon-diving down to double-digit floors in "search" of the coveted orb. The catch? They already have it! Not that the top agents of the international espionage scene tailing them know! And speaking of tails, their loyal hellhounds might be the only thing standing between them and an assassin's aim!