While delving into the first layer of the Abyss to search for relics, Riko and her partner Nat become separated. Spotting a beastly serpent called a crimson splitjaw nearby, Riko uses her Red Whistle to draw its attention in order to save Nat from being eaten. Despite Riko getting cornered by the crimson splitjaw to the point of almost becoming devoured, the crimson splitjaw is suddenly chased off by a powerful energy blast...