"Piece of memory2 prologue" is the sequel of "Piece of memory". You can play without completing "Piece of memory", but in order to understand and enjoy the background, we recommend to play and complete "Piece of memory" first. Lily and Nekokun landed on the Earth where the environment has been drastically changed because of the crashes between the planets of the solar system. After they have awaken the people from cold sleeping, they became unconscious and heard Lily's mother's voice to. They must go to the Dome, the Global Environment Inspection Bureau. Sneaking in a freight train they are now heading to the Dome.