Psyren

One day, high schooler Ageha Yoshina picks up a mysterious “red phone card” left behind in a public telephone booth. A few days later, his childhood friend and classmate, Sakurako Amamiya—who possessed the same card—suddenly vanishes without a trace. In search of her, Ageha finds himself drawn into the rumors surrounding a nationwide string of mysterious disappearances, said to be the work of a secret organization known only as “Psyren.” When he accesses the group, a deadly game begins—one that will change his fate forever.

(Source: PSYЯEN Official Site)