This work is an action-adventure game released by Borstech in 1986. The main character was floating as a spirit in a ruin that suddenly appeared from under the sea. There is no explanation as to why he became a mental body or what the protagonist must do, and as you explore the ruins, you get a vague picture of the situation. One of the highlights of this game is the system called Spirit Ride, which possesses the defeated opponent. Attack methods and durability differ depending on the possessed body, so the key to success is deciding which creature to possess as you continue your exploration. Furthermore, the items you can obtain will change depending on your actions, and the story development and ending will also change, so it is up to the player to decide how to proceed with their exploration within the ruins.