In the center of a remote island, there is an unconquered mysterious realm - Abyss.This is a huge and dangerous, bottomless abyss, housed with strange and insolvent creatures, and only the bravest adventurer dares to go deep into it and pursue the traces of ancient relics. In the deep and pure upper area, Riko, a girl with a dream of exploring, accidentally encounters a mysterious little boy.At that moment, the gears of destiny quietly turned, and a journey of courage, secrets and growth was slowly beginning.