Having triumphed over the grueling trials of Idofront, Riko now wields a White Whistle, granting her entry into the sixth layer of the Abyss—The Capital of the Unreturned. With Reg and Nanachi by her side, Riko embarks on a journey to navigate this unknown territory, where the ruins of the fabled Golden City await. Adapting to the unforgiving surroundings, the trio faces perilous creatures and unfathomable landscapes. Their path leads them to a village inhabited by enigmatic beings called 'hollows.' Despite the eerie atmosphere surrounding them, the determined trio presses forward, delving into the secrets of the settlement and the forgotten tales of past explorers lost in the depths of the mysterious Abyss.