Protagonist (known as Minato Arisato in the manga) is the main character in Persona 3. He is a transfer student that is sent to Port Island, where he ends up signing a contract with some young boy. The Protagonist stays at a co-ed dormitory, along with many other characters, where his progress is monitored. While being attacked by Shadows at the dorm one night, he awakens to his powers of Persona.
Outside of Persona 3 and its ports (Persona 3 FES and Persona 3 Portable), he is mentioned in Persona 4 and in Persona 4: Arena. He is also set to be one of the protagonists in the upcoming game, Persona Q: Shadow of the Labyrinth.