Seven years ago, alien Creatures sent meteor fragments crashing across Earth. Their impacts opened dimensional rifts known as Gates, releasing monsters that devastated civilization and left much of Korea in ruins.

Some humans exposed to the alien phenomenon became Awakened. Espers possess supernatural abilities, but using them accumulates unstable energy. Excessive buildup can trigger Overdrive, causing them to lose control of their powers and themselves.

Guides are rarer Awakened who can stabilize an Esper's energy through physical contact. More intimate Guiding is significantly more effective. Compatibility between an Esper and Guide also affects its efficiency.

Survivors now live among ruined cities, safe zones and territories controlled by factions such as Daybreak Dragon, New Tiger, Taeul, 710th Commando Regiment and S.E.M.A. Others survive independently as Wanderers and mercenaries.

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During the First Gate Incident, medical student Gaon was struck by an alien meteor fragment that embedded itself in his chest, leaving him in a coma.

For seven years, Gaon's family kept him alive while paying tribute to Daybreak Dragon.

Days before his awakening, the Creature known as The Drifter attacked his family, drained their energy and abducted the unconscious Gaon.

Gaon finally awakens after seven years.

The last world he remembers is ordinary Korea before the Gates. He knows nothing about Espers, Guides, Overdrive, the factions or the society that formed while he was unconscious. He also doesn't yet understand what the meteor fragment has done to his body or that he has awakened as an exceptionally powerful Guide.

In the aftermath of his abduction, Gaon's path crosses with Guest, an experienced Esper and mercenary.