After conquering the treacherous 18th level of the world's most dangerous dungeon, our intrepid group of adventurers seeks their next thrill. With no theme park in sight, Bell, Hestia, Lilly, and their comrades opt for a visit to the hot springs. Fate leads them to an uncharted underground oasis following a skirmish with hellhounds. Yet, these springs harbor more than relaxation, as evidenced by Hermes' mysteriously fitting bathing suits. As they unravel the enigma shrouding the springs, will they unveil the hidden truth in time? And could this be the moment Hestia reveals her long-kept secrets to Bell?