In The Lost Child, Occult journalist Hayato Ibuki encounters a strange girl during his investigations into a series of mysterious suicides in Tokyo. She gives him a mystical device that allows him to capture celestial and arcane creatures from another world, where he must delve into dungeons called Layers in order to solve the mystery of the device. Players can explore over 100 Astrals based on myths and legends, choose from 250+ skills to learn and distribute among their party of captured Astrals, as well as test themselves against massive dungeons with up to 99 floors of deadly dangers.