Players can create up to five personas called P:\. These act the same way computers in terms of storing memory; everything your character does is remembered in their personal database, sorted by folders (which can be sorted by months, days, years, even hours and seconds.) which can be deleted at anytime but must be disposed.
Folders can also contain programs which can do a variety of things, ranging from skills to how your character looks and acts.
The player may freely roam over the world called the System, which is an open world environment consisting of cities, dungeons, towns, "dreamscapes", artificial nature reserves, abstract areas, and villages. The player may navigate the game world faster by riding motorcycles, or by utilizing a fast-travel system that allows them to warp to previously-discovered locations. The game's main quest can be completed or ignored at the player's preference after the first stage of the quest is finished. Non-player characters populate the world and can be interacted with in a number of ways; the player may engage them in conversation, marry an eligible NPC or kill them.
Set in a world called the "System", the System has been in peace for years until a man known as Virusu the Intruder entered into the system under the guise of a trojan horse. Your P:\ character is a imprisoned persona and set to be deleted until Virusu appears and frees some deleted Personas. In the confusion, you manage to escape.
Each persona has their birth dates assigned by the zodiac symbols. It also effects personality and your horoscope.