Ageha Yoshina is a confident high school student who offers his services to help others—for a price. One day, while returning home from a job, he discovers a mysterious calling card bearing the word “Psyren” in a phone booth. Curious, he decides to keep it, unaware of the danger it holds. The following day, he discovers that his classmate, Sakurako Amamiya, possesses an identical card. When he confronts her about it, she desperately begs him for help, marking the beginning of a series of bizarre and terrifying events.
Soon after, Sakurako mysteriously disappears, leaving Ageha determined to uncover the truth. He calls the number printed on the card and is greeted by a strange voice that subjects him to a series of questions before posing one final, chilling inquiry: “Would you like to go to Psyren?”
Thus begins a deadly game of survival for Ageha and Sakurako in a mysterious world teeming with monstrous creatures known as Taboo. Armed with extraordinary psychic abilities called PSI, the two teenagers must fight their way through this hostile realm and find a way back home before it's too late.