Psyren (Japanese: サイレン, Hepburn: Sairen) (stylized as PSYЯEN) is a Japanese manga series written and illustrated by Toshiaki Iwashiro. It was serialized in Shueisha's shōnen manga magazine Weekly Shōnen Jump from December 2007 to November 2010, with its chapters collected in 16 tankōbon volumes. The series follows Ageha Yoshina, a high school student chosen to compete in the Psyren games—a deadly contest set in another world. In North America, Viz Media licensed the series for English release and serialized it in its Shonen Jump magazine.

After defeating a bully for ¥10,000, Ageha Yoshina heads home, expecting a reprimand from his sister for breaking curfew. On the way, a nearby pay phone rings, and upon answering, he hears only his own echo. Dismissing it, he hangs up but discovers a mysterious calling card inscribed with the word Psyren. Intrigued, he visits his school's Occult Club and learns that Psyren is an urban legend promising a ¥500 million reward to anyone who uncovers its truth. Later, he finds a classmate's wallet—belonging to Sakurako Amamiya—which had been hidden by other students. Inside, he spots an identical Psyren card. After returning it, Sakurako flees, whispering "Save me" before vanishing. The next day, she is reported missing.

Determined to find her, Ageha calls the number on the card and undergoes an extensive quiz via pay phone. At the end, he is asked if he wishes to enter Psyren. The following day, while fleeing two impostor police officers, his phone rings. Answering it, he is abruptly transported to Psyren—a desolate wasteland overrun by monstrous creatures called Taboo, later revealed to be former humans transformed by the organization W.I.S.E. A mysterious voice, Nemesis Q, assigns missions to participants, warning that failure to comply means being trapped in Psyren forever.

Upon their first arrival, newcomers are given strict rules: avoid the towers, never lose their cards, complete the game before the number on the card reaches zero, and never speak of Psyren to outsiders. Exposure to Psyren's polluted air alters the Drifters' brains, unlocking latent psychic abilities known as PSI at the cost of severe physical strain. PSI manifests in three forms: Enhance (physical augmentation), Blast (external energy projection), and Trance (mental manipulation).

As the game progresses, Ageha and his companions encounter a group of psychically gifted children raised by Elmore Tenju, the elderly woman behind the ¥500 million bounty. Each child possesses unique PSI abilities and traumatic pasts, trained by Tenju to oppose W.I.S.E. Ageha trains with them, honing his powers before being summoned back to Psyren.

Eventually, only Ageha, Sakurako, Hiryū Asaga, Oboro Mochizuki, and Kabuto Kirisaki remain. They receive further training from former Psyren participant Matsuri Yagumo and the Tenju Roots Orphanage children. Meanwhile, Miroku Amagi, a psychic from their timeline, is exposed as the leader of W.I.S.E and the architect of Japan's impending ruin. His actions reshape the Psyren timeline, ensuring the orphanage's survival in that dystopian future.

In the Psyren timeline, Mithra—a W.I.S.E psychic—reveals she has manipulated Miroku. She explains that the meteorite Promised Tear fused her with Ouroboros, a planet-consuming entity, and summons it to Earth. Before annihilation, Nemesis Q's overseer, Grigori #07, returns the group to their original timeline. Ageha and his allies intercept W.I.S.E before they secure Promised Tear. Ageha provides Miroku with a card from Grigori #07, showing him the catastrophic future. Together, they defeat Mithra, but Ageha falls into a coma.

While unconscious, Grigori #07 contacts Ageha, revealing that in the Psyren timeline, Miroku and Grana sacrificed themselves to destroy Ouroboros and Mithra. Upon awakening, Ageha reunites with Sakurako and liberates Grigori #07 from captivity.