Riko decides to descend into the Abyss in order to find Lyza. However, Nat openly opposes this idea, believing that Riko will never return to the surface by doing so. When Reg does his first delve as a Red Whistle with Nat into the first layer to search for relics on the next day, Reg believes that he will find answers to his own identity and lost memories in the Abyss by joining Riko...