Chaos descended upon society with the appearance of the Gates. During a time when monsters poured out of these Gates and only turmoil existed, Espers and Guides began to manifest.

Those who possessed supernatural powers and could fight the monsters were called Espers. However, the more an Esper fights and uses their abilities, the more their internal wavelength becomes unstable, eventually turning them into a ticking time bomb destined for a violent rampage.

Guiding is what stabilizes an Esper's wavelength. The more physical contact there is, or the deeper the intimacy, the faster and more easily the wavelength stabilizes. Of course, the matching rate between the Esper and the Guide is also a crucial factor.

Facilities were built to manage Espers and Guides, and society began to regain its stability.

Childhood friends who grew up together, Yohan Go and Guest. Their friendship continued until it was abruptly severed by the Gates.

When the Gates opened and society fell into chaos, Yohan manifested as an Esper. As an S-class Esper, he was thrown into the front lines, rolling through one battle after another. The time they spent together dwindled until, eventually, three years passed without them seeing each other's faces.

In the early days of the chaos, Yohan led the charge in clearing the Gates, but with his wavelength increasingly misaligned and no Guide with a high matching rate available, he became a ticking time bomb.

After three years, society has finally found peace again. And then, Guest suddenly manifests as a Guide.